I try to have no more than one of each type of cameras loaded with film at any time, because I want to fill and develop the films not too far in the future, and because I like to have some cameras empty to fiddle and play with. Usually loaded are:
A compact I carry everywhere, but rarely use (these days a Ricoh FF-1).
A medium format camera, usually a Minolta Autocord, mostly reserved for deliberate stuff from a tripod.
A 35mm RF, one of two Canon LTM bodies, P or 7.
A 35mm SLR, most of the time a Minolta XD-7, but right now a Pentax MX.
A few others get fed some film from time to time, maybe I should consolidate to those I use frequently.