I just noticed this.
But shouldn't an aslaran, theoretically, be able to writhe
faster than say, a dwarf?
Based on the logical concept that getting out of bonds counts
only on the size of the bounded, but also their dexterity, with
clumsy small person getting out slower than a slightly larger,
but more dextrous foe?

Size matters

But I guess dex+size/2 makes more sense then just size.. up to the coders I suppose.

I know size matters, but shouldn't dex matter as well, really?
*Considers getting a pollathon going*

Not really any point to changing it. Use diminish. Or just use invoke summer/evoke tipheret

I stopped caring when people started writhing out of crucify less then a second after I regained equilibrium. I've also stopped wasting hangedman cards on anyone that writhes. Abjure web is a much better use of my mana and lets me make more hermits, magicians, catacombs and aeons.

Just because it might make sense IRL doesn't mean it needs to be changed in-game. As long as the "Size determines writhe speed" isn't creating an unbalanced game (it isn't) there's no need to change it.

how high is summer in low magic anyway?

Last Lowmagic I got, and I'm at Master.