yeah stress is a killer, no need for it . great you care so much though
im not sure exactly, but must be just about every day they pass a stool. every couple or 3 is probably ok, it does vary abit though, depending on growth/age what and how much your feeding etc. I dont really pay alot of attention to the smelly presents lol, but do notice if there's nothing to clean up for a week or more, thats when id start to ponder whats up.
atm mine are eating like crazy though, and seems to be every day if not every second.