Actually I routinely stat up my casters with rotes that are higher than my conviction.

What are the higher stress boxes on my character sheet for anyway?  Also if you're going to take a consequence for casting a spell anyway, whether it's two stress or four why not get the full benefit of it?    So yeah, if I have a lore of three+, I'll usually have a 1 stress, 2 stress and 4 stress rote, likely using focus items to get enough discipline to control the 2 or 4 stress rotes (sometimes I just accept I'll be invoking an aspect or having backlash/fallout to control the rote if high enough discipline isn't in the cards)

So instead of getting, say, four rotes with 6 shifts each that I can easily control, I'll have a 6 shift, a 7 shift and a 9 shift rote that take more stress to activate, but make better use of my stress box resources (after 3 spells, I'm taking a consequence anyway to get the 4th, and if I'm gonna take a consequence I might as well get a 7 or 9 shift effect instead of a 6 shift one....)

But that's just the spell track.  If I'm looking at a warden type, somebody who expects to get into fights, that person is going to have a way of laying down the hurt with no spell at all (weapons, guns, something) or he's going to have enchanted items that accomplish the same thing with enough uses to get me through a hard battle (see Dresden's ring, his potions, his belt buckle in one adventure, an animated electrical cord+plug in another etc).    He might also have social skills, to get advantage through banter (Dresden's constantly using intimidate in fights to piss people off instead of just blasting them) and if none of that seems like enough, most wizards with thaum can spend a few minutes generating several spells that give them other advantages the next time they get into a fight in a day when they've been filling their consequences up.

Of course I'm willing to play 1 conviction spellcasters, spellcasters with zero lore skills, etc.  My generic wizard though is going to be able to routinely bust out 7-9 attack roll/7 shift area and single target attacks/maneuvers/blocks/etc (I tend to use extra shifts from high mental stress attacks on areas) in their specialty and a little less in areas they aren't as good at (generally similar power, less accuracy).   That's the benchmark you're looking at without any points spent in refinement, and at least 30 skill points to play with.  It's a measure nobody but a caster can manage, not even with military explosives..you're looking at more like what a fully crewed APC might bring to the table, maybe even a main battle tank.

Yeah, I can only do 3 of those a fight, 4 with short term consequences, 5 if my conviction is 5 for some reason.  More if I have sponsored magic.  If you can't win a fight with those, you should probably be thinking about running away or conceding anyway.  If you're not sure, use your non-spell options and keep your powder dry.

In theory yes, but once the compel is accepted, you don't really need to focus on it at all anymore. The shifter just won't be able to shift for as long as was agreed upon in the compel.

Unless they spend a fate point to ignore the compel.

That's my problem with the maneuver/compel approach.  It takes things out of the realm of skill vs skill and action vs action and into the realm of "who has the most fate points".  Fate points help a lot against blocks, but they're not "I win" buttons by themselves just because of the mechanics of how the maneuver was set up.

Now actually, compels don't always have a scenewide duration.  If the condition that caused the compel is removed, the compel is removed.    If you're holding off a vampire with a ray of sunlight caused by tearing away a curtain, somebody could remove that aspect from the scene by moving something in front of the window or spraypainting it black or similar.

The difficulty number for removing an aspect is the roll you used to establish it...same as a block.  But something like taking a curtain down is clearly a maneuver, it establishes a significant change to the environment.   Holding off a vampire with a cross and conviction, by contrast is a block.  It takes continuous action to sustain, and if you're forced to take some other action it goes away, and can be destroyed by attacking YOU, not attacking an aspect on the scene.

Which action is which is a matter of flavor of how you establish the maneuver/block, not the sort of action you're trying to prevent.  That then establishes what remedies are possible beyond overcoming it with an appropriate skill (raw fate point outspending to not be compelled at all vs a third party doing something unrelated to the block to interfere with your ability to maintain the block)

I do like "shifting blocked" as a consequence option to an attack.  We've certainly seen that with Harry sometimes with respect to his own magical talents, being too concussed to focus on a spell or inflicting it on himself when overdoing magic with the "super caffeine" potion.  But the victim of the attack has to agree to that consequence, ditto with conceding.  Taken out...oh yeah.  They're allowed to completely transform you (ie kill you) with any means at their narrative disposal, so all sorts of gruesome possibilities are on the table.  (can't magically block shapeshift without magic, can't drug you into being unable to shift without drugs, etc)

I've played with this quite a bit for theoretical builds.  I'll likely want to try one of these ideas someday.

Obviously SU speed, or mythic in a high refresh game.

Stunts like "too fast to react" (athletics for stealth Ambush trapping) or "plenty of time to react" (athletics instead of alertness to spot an ambush) can add a lot to the flavor.

If you're really high end (like DC's flash character, rather than somebody who's just very fast), consider thematic Channeling (Super Speed Tricks) and your focus item might be something like the Flash Suit (you can't go to extreme super speed tricks without protection).   A "flash suit" could instead be an item of power, perhaps provided to keep your super speed from tearing you apart (maybe you can only do inhuman speed+stunts without it), provided by a friendly magical patron.  The Star Labs scientist on the 1990s TV show provided the Flash Suit for that reason.

Feeding dependency would fit the TV show pretty well, when Barry Allen used his powers much he would literally starve unless he had a bunch of food on hand to devour.    Some kind of recovery power tied to a feeding dependency would also make sense (you heal fast, if you can rest/eat).   

Power.....

Scion of Hermes or similar speed oriented entity could work.  There are probably some messenger angels that might apply too, or diabolic influences for that matter.  Or you could just go the Focused Practitioner route, you're a mortal whose magic is just all about moving yourself around quickly and safely.

Again, just stealing ideas from the 1990s TV show, Barry Allen is a mundane who had a magical accident, then hooked up with a white court wizard who provided a suit that helped him control his power, in exchange for favors/future services, plus lore stuff to let him know important things like he could kill himself with hunger if he overdid things.

A changeling is possible but a super-speedster is likely to have gone all the way over to Fey side.  A Fey who got fascinated by superheroes might be kind of fun.   Dewdrop faeries are REALLY fast.  What if one of them figured out how to make a human sized body out of ectoplasm, but kept the speed?  (too heavy to fly, but still super fast).   (shapeshift, where your shifted form has dim size/flight, your "human" form is an ectoplasmic exoskeleton, maybe the costume hides how it isn't a very good copy of a human....).   

Ok, more geeking on using "intimidate to move".

You can move one zone if you have no obstacles to moving, with -1 to any other action you take.

Rapport draws a crowd determined to stop you from moving (reasons vary.   shifts to overcome based on rapport outcome)

Athletics has the sprint trapping, which lets you take a sprint action to bypass obstacles (sprint vs rapport to set up block).  Sprint just lets you go by, doesn't let you destroy the crowd.  No -1, because sprint lets you move anyway.

Might has the "exert force on others" trapping.  With Might-1 you can push through the crowd and still move if you get enough shifts.  The crowd will still be there, it'll close in behind you.  If you want to disperse the crowd violently using your strength, you probably need to use Fists, with +1 if your might is better than fists and -1 for supplemental action.  You're hurting people and tossing them out of your way or trampling them instead of just pushing through them.  GM might rule that extra shifts in damage from super strength or claws might contribute to the overall score, but give you social stress equal to the extra shifts or something to indicate the extra violence.    It's the same reasoning a GM has to use when deciding if a high fists roll can get you through a wall....sometimes strength and claws will help a lot, sometimes it's the precision of the fists alone that matter.

Intimidate could go two ways.  Using the Brush Off trapping people move out of your way, so they're not an obstacle....for you, if you roll intimidate-1 you can move a zone.  Using intimidate as a social attack, you can actually disperse the crowd for everybody, not just you, again with intimidate-1 if you want to move in the same round.  Weaponized fear attacks would add shifts to outcome, which might help in dispersing the crowd if GM thinks it should.

Blocking a block....

You want your friends to be able to run away.
You are facing Harry Dresden, who is known to put up force walls, or sheets of flame, and don't want to him to do that.

You could explicitly set up a counterspell against that type of magic if that's your thing, or you could shower Harry with gunfire, forcing him to protect himself with his shield spell instead of doing anything to prevent escape, or you could flood the escape path with running water by aiming your fire hose on the escape path (weapons?  Guns?)

It seems like an awfully specific action.  But blocks do tend to be that way.  It's deeply important to stop one specific option from happening, so you devote your action to eliminating that possibility, or at least making it very hard.  Harry must choose another action (eg, blasting you with Fuego or his pistol instead of using force or fire to set up a barrier) or try to overcome the block (drawing on his conviction and spending a fate point to invoke "The Building was on fire and it wasn't my fault" Harry gets a sheet of flame going anyway, blowing past the attempt to suppress his magic )

That's where it gets interesting.  I might be inclined to allow a wizard defending against Harry to set up his block as armor instead of a flat number, to weaken the force wall/sheet of flame regardless of how many shifts Harry put into it, instead of trying to block it entirely.  That might be a better way to simulate the fire hose approach too.

Given that in all the Fate systems, including DFRPG the idea is to expand player narrative options, not restrict them, I'd say yes, a counterexample against the four stated actions is a pretty compelling argument, especially since it is easy to imagine blocks against other actions not included on the list of four.

Really, anywhere you can imagine a maneuver that is invoked for effect, you can imagine a block.  The primary mechanical difference is a block requires constant use of your actions, where a maneuver establishes an aspect that fate points can be used to invoke or compel regardless of skill die rolls, but don't require actions after you set them up.

One more response on the "you can only block attack, defense, maneuver, movement" is a Veil doesn't block any of those.  It is explicitly a block against Alertness and Investigate, which is none of the above.