Totally depends on your situation. In traditional
theatre, yes, the electrics are generally trimmed out so that they cannot be seen from the audience. There's no rule saying you have to do this, however. Many shows, RENT being a good example, intentionally leave their electrics totally unmasked so the audience can see all the lighting equipment in the air. But for a general high school multi-purpose
theatre, keeping the electrics trimmed out of sight is probably a good idea.
If you're really not getting enough
intensity from your units at those high
trim heights, you may need to change some things.. For the fresnels, try spotting them down a
bit so they're not set to as wide of a flood. By spotting them down, you will decrease the area covered and increase the
intensity of the
fixture - so when it's flown to a higher
trim height, you should get a brighter coverage. For the
PAR cans, you may need to relamp them to a tighter spot. I'd guess that your PARs are probably lamped with WFL lamps right now. By changing the lamp to a MFL or even NSP lamp, you will again get reduced coverage and increased
intensity, which will help you at the higher
trim heights. While the
intensity won't be identical to what it would be with the WFLs at a lower
trim, it will be fairly close.
And if switching things around like that isn't really an option, there's no rule that says you need to have the tallest
stage possible. Just
trim your electrics to the highest height where you can still get usable
intensity, then
drop the borders in to mask the electrics.