The NPC had made a few assessments about the PC/scene that she could tag using empathy and awareness. She'd also done some scene-long naval-gazing maneuvers.
An aspect from most maneuvers has to be used
as soon as possible, or you lose the free tag. So you can't stack up multiple aspects from navel-gazing maneuvers. You can still stack free tags from declarations and assessments though.
First of all, a 24 shift attack from a pure mortal (or anything less than a faerie queen, really) is pure bullshit.
No, it isn't. It merely requires special circumstances. Ritual magic can easily pass the 20-shift mark. A sniper who spends several exchanges making assessments and declarations about vantage points, firing angles, cover and open ground, and then finally aims and fires with all those free tags can also get that headshot without any warning. A wizard attacking at weapon 10, control 10 is making essentially a 20-shift attack. A vampire that attacks under cover of darkness so you can barely see it (stealth+cloak of shadows declaration or maneuver), jumps from atop a car so it has higher ground (alertness/athletics declaration), has waited until you reach the part of the road the heavy rain has flooded (alertness declaration of "slippery terrain"), has assessed your combat style (aspect assessment on you using fists skill), has a base attack skill of +4 and uses his supernaturally strong and clawed hands attacks at +12 with weapon 6, effectively a 18-shifts attack.
And all of the above have happened in-game one time or another to me or by me.