We can't use them during seasons,so it is mostly a summer thing.During that time of year,it is a good idea to check them weekly as one weed growing up in front of the camera,can blow in the wind and cause a lot of false triggers.The battery life of your particular camera may determine the longest time you can leave them.Some areas,it may take more than a week to get meaningful pictures.Other places it may happen daily.A week seems to work for me but often I can't make it that quick.I find it nice to just get out and check them any time I can.