Batteries, what are those? Don't use them in my medium format cameras! Grins & Smiles!
But for cameras that have batteries for more than the light meter I only take them out when I re-charge them. The film cameras that have a button battery for the light meter I only replace when it's dead. When I make pics at an important gig I charge everything up before the event takes place, camera batteries, flash batteries, the ones in each piece of equipment as well as backups. I turn off the cameras, flashes when the gig is over.
Hope this helps you.