It all depends on the time of year and what your set up on.During the summer watching soybeans I will check them at least once a week to make sure its in the right spot. During season over scrapes or the mock rub trees on feeding fields about the same, at least once a week, to make sure everything is still up and working and to get the info for which fields I should be hunting. I like having as much of the field/clover as a background to see when and who is useing it. If the cameras are set on trails in the timber, which I dont like to do, leave them as long as you can. Deer seem to avoid cameras on just trails unless they are mounted high up, pointing down.