I played around with the demo setup a bit more, cutting the number of tablets down from 12 to ten (which is just, juuuust enough to show the twill pattern rhythm, and the block that forms when a diagonal is cruising its way across the stack of tablets). I've also changed the sequence a bit, including a tiny strip of double face now, then diagonals, then diagonal patterning, and finally a little bit of patterning on 3/1 broken twill (which includes the crux of the thing, the direction change in twill background).
Cutting down to only ten tablets did make a difference. The larger difference was probably made by me abandoning my lovely, trusty weaving knife in favour of just the finger, and not bothering about the fact that my band width is not so even, and the wefts are sloppily tightened.
30 minutes is still a very, very short amount of time. It also still results in a very short bit of weaving:
However, the new sequence means I can explain things better as I go along, and that I can, miraculously, squeeze all the important bits into my time slot. Hooray!
Now I only have to make a suitable warp for the conference demo (as I've used up the one on the picture), make sufficient notes of what to do and what to explain at which stage, and then do another practice run or three shortly before the conference.
Which means that I'm now free to work on the other NESAT presentation - also about tablet weaving, but entirely different bands in an entirely different structure. Fun things!