Summer magic allows for evoc speed minor healing, and at 6 shifts you can give 2 fragile
Aspects that buff physical actions. It is very handy.
Indeed, and note that normally with Evocation you can only give one aspect (non-fragile with more than 3 shifts for a buff at the crappy rate of 1 exchange per extra shift). Thaumaturgy at the speed of Evocation allows for far longer-lasting spells than normal (really, Soulfire should be taking this into account with Conjuring and such in some manner).
Another way to look at it, is think of any effect an enchanted item could do. If it falls under your Sponsored magic, then you can do it like an evocation. For instance, Sponsored Magic: Amun-Ra could create true Sunlight as an evocation. Perfect for those dang vampires.
If you have a Sponsored Magic that allows some kind of divination, then you could potentially grab someone in a fight (use maneuver to represent that), and tag that for a Thaumaturgy-like Evocation spell that lets you learn something about them (like the Catch potentially for someone thing you have to personally know -- you got the whole guy right there for a thaumaturgy ritual, can't be that hard at that point!)
Winter can be used to put a guard to sleep for instance.
Also, these things say that they can be used "as an element in evocation." That means that if you specialize in Winter Magic as evocation or make a focus, you can do cold stuff, sleep, decay, etc all as the SAME element. That's pretty cool. So even if a lot of that is stuff that's evocation anyhow, having it all as a singular element is pretty helpful. At least, that's my read on that part.