DraQ
Arcane
Even compared with the other main contender that is XP-based?Train by use always seemed nonsensical to me from a realistic viewpoint.
The main problem with use-based is balancing realism and fun (as in finding ways to excise boring stuff without also creating imbalance and giving player free lunch) and creating rules to avoid loopholes that allow mindless grind in the first place, but given that use-based is heavy-weight system with a lot of logic under the hood it's a given that getting it to work requires investing some effort up front.
Part of the former problem can be handled neatly by assuming that the PC(s) do their training routine as part of their camping, so you only give player their skillgains on rest (also obfuscating and delaying, possibly randomized, feedback) and you can cap them in all sort of useful ways.