Fwiw I'm going back to my original hypothesis and saying there's no limit at infinity, but there is a class of questions that are in none of the levels, essenti

Fwiw I'm going back to my original hypothesis and saying there's no limit at infinity, but there is a class of questions that are in none of the levels, essentially meaning you can't prove anything about their solvability. It's impossible to prove that any particular question is in that class, by definition, but it may be possible to prove that there exist questions that are. Which opens the philosophical question of why so many questions aren't.