I can play stuff [classical guitar]I know very well without sheet music but most stuff needs the music or i get “lost” somehwere
This is true, I’ve about 8-10 pieces i can play without sheet music, I’ve a load of other stuff that i need the music to remember it as i dont’ play it that often.
Suppose that also opens up, are all the member of the orchestra full time? as if not that could be another reason, that some are just session musicians, so they do need it.. When you get to the higher level of soloists etc with established repertiores, I doubt they need it at all, and will have things well practiced.. I know i’ve watched alot of classical guitarists that don’t use sheet music in performances.