I assume you're concerned mainly about body mics, since you mentioned the actors.
Our lavs are taped over the ear on the cheek, so we need to do a volume check before each show because the positioning (and therefore input volume) will change.
We put mics on about 45 minutes before showtime, and around 10-15 before showtime I get on the clearcom with the backstage manager and have him/her grab the actors one by one, bring them to a place where I can pick them up (fortunately I can pick them up from our Green room), and have them belt out a few lines of song or dialogue. I listen through my solo monitor headphones and mainly adjust the input
channel gain on the board, and very infrequently I will need to adjust transmitter or receiver volume or reposition the lav.
And, if for whatever reason we run out of time to do official mic checks, I'll just get on the solo headphones and cycle through the lav channels to make sure each one is picking up whatever is going on back there loudly and clearly.