On the other hand, we got a 26-shift entropy curse that is about finished in a couple of minutes and Victor Sells summoning a demon (10 shifts summoning?) in under a minute while Harry is ducking behind a sofa. Harry similarly casts a Ward enough to block said demon in the time it takes the demon to break his basement door and tracking spells fast enough before an arsonist has time to flee a couple of blocks.
The Entropy Curse had a lot of things going on with it, and some serious concerted effort by multiple people. I would personally allow something to be done quicker if there were several people working on it.
As for Victor's demon, I could just as easily see it as already summoned, and (woo game mechanics) Victor spending a Fate point for a fortuitous arrival, or simply having him appear because he was already bound and watching from the other side just out of reach. If that was the case, it was less a summoning and more an evocation to open a Way to the Nevernever. That's easily doable in a round.
Concerning Harry's Ward: it's been a while since I read the book, but weren't they standing in the prepared circle Harry had, designed for summoning? Perhaps he already had a Ward in place, and simply put forth some power to activate it. (which would be a rockin declaration)
Tracking spell on the fly? The dude has just left? The actual difficulty of that roll would be really low, 2-3 shifts I'd think in a regular investigation roll, and 2 minutes isn't that bad of a lead in a scene like that.
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To clarify, I'm not saying I disagree with you, just offering alternate game explanations for these things. The most important thing is always going to be the drama of the scene and what is the most fun to have happen. That will always supersede hard and fast rules.
That said, I like the complexity::minute ratio. It sets a semblance of time for the players, so that they have some idea of how long things will take before they ask. Also, if Thaumaturgy is interesting because of drama and creativity induced by either a time limit or creative description, then this always places a time factor on it, and brings that idea more readily to the forefront.