By why was Button so insistent that good fast spins used more energy than jumps?
Probably because his programs back in the day were mostly filled with Doubles?
I jest, I jest.
The spin issue is an interesting one. I believe the spins that take up the most energy are the ones that require you to spin the fastest or hold your body in a precise and difficult position (while remaining centered of course). However, CoP doesn't currently reward those spins the most. Every "difficult variation" is not equally difficult but the system credits them as such. Gaining levels with so called "difficult variations" is also more favorable than spinning as fast as possible in a good basic position.
The ideal "basic" spin position for the Sit Spin is actually HARDER than some of the so called "difficult variations". Doing a sit spin with a completely straight back, completely extended free leg, and the butt below knee level is really a more difficult position than many of the catch-foot or cannonball/pancake sit spin positions we see. And yet that "basic" position doesn't count as a feature while the other "difficult" positions, that are both easier and often look worse, do count. The classic sit spin position should really count as a difficult variation. The classic layback, with a great arch in the back and the blade of the free foot parallel to the ice, also should. Same goes for the classic camel, with the upper body facing downward at the ice, the back well arched, the free leg fully extended, and the free foot level with the head.