Don't use a flute patch 2 octaves below C or a contrabass patch 4 octaves above C, respect the "true" frequency range of the patch

If you're going for realism, then yes. If not - push the ranges, see what happens.

(Actually I disagree with the idea of using many different reverbs. Your ears will pick up on it and it will sound unnatural. IF you do this, turn up the reverb until you can hear it, and then dial it all the way back until it seems to disappear.)

I believe it was Zappa, trying to rescue his LSO recordings, so he placed each section in a different 'atmosphere'. Sorry, on mobile but I'm sure it's mentioned in (at least one of) his book(s).