I check mine atleast every 2 weeks. I usually go once a week. Theres a couple reasons.

1. Why have it up if there is no action in that spot? I like to move them around even if its a 100 feet andfacing a different direction.
2. Pictures of nothing. A tree branch swaying can eat up batteries and a memory card fast. I do trim around for this but even a branch 20 feet away can set it off.
3. To get out of the house and down to the hunting land. I do take my hunting pants and boots and spray down before I head in. Just a little precaution.