scheme that requires most skills to handle - Elite
You have a large array of weapons and you gotta be able to execute with them. Many different properties and dynamics you have to be familiar with. Also, you need smart tactics in the first place and the skill to pull them off. Also, there are luck factors in elite and you need skill to counter those.
As for ttrr, sure it takes a lot of skill, but compared to elite, idk... Is ttrr pure skill or is a lot of it muscle memory? Imagine how many times you've climbed or scrolled in a ttrr, there has got to be some muscle memory there, especially if you are pumping around the place... I doubt you can actually look at your worm going at those speeds and ready your finger to press the space at the right time.... a lot of it has to be experience and memorizing the timing for those things to work out.
If the question was which scheme had the least amount of luck, ttrr would win hands down, but that doesn't mean it takes the most skill to handle...
Bng? uhh, sure, those shots are pure skill, but to me, it is like getting a strike in bowling... it is a lot easier to get a strike at bowling (bng) than to make a half court shot in basketball (ttrr)... one is just more extreme...
anyway, idk why i wrote all of that because the scheme are so different... it is like comparing football, basketball, hockey, and baseball.... baseball wins hands down, by the way. who wants to argue that?