I don’t just mean “faking” harmony in the jazz sense, but rather more generally.
Got involved in a little discussion recently about how to play complex cross-rhythms over at Adam Neely’s YT channel. When presented with something like 3s on 5s some people (me included) advocate learning to feel the way the two sound and work together whereas others like to rigorously reconceptualise it by a sort of common factoring process. And if you don’t have time to do either – fake it. Both sides agree on that.
There was a rather scandalous piece that was published in The Strad a while ago about how often (surprisingly often) and why (for good reasons) even the most accomplished professional classical string players fake demanding passages – both notes and rhythms. Well worth a read – it even includes some handy tips, a lot of which can be translated to other instruments.
I’ve written stuff for all kinds of ensembles and I expect them to approximate the score here and there, particularly when rehearsal time is short – in fact, sometimes I quietly advise them to do it. They know and I know… and it’s okay…
It’s a bit like sight-reading – do your best, but whatever you do, keep going and try to lock back in as soon as you can.