About once a week, but no hard and fast routine.
Tell you what I see every year, and I think this ought to be teaching us something about deer behavior. Normally I put a camera out every year around mid August to early September. Feeding corn and rice bran, I'll start getting pictures within days. Even with me going in there AT LEAST once a week, sometimes even jumping them off the pile of corn/bran, I still get daylight pictures every day. Doesn't matter if it's a doe & fawn, or a batchelor group of mature bucks, they don't seem to be affected by my routine. They'll be there all times of the day and night really, my intrusion seems to make no noticeable difference, they come every day. Taking it further, not regularly, but often enough, I'll take feed in there and the next time I check the camera I'll have deer pics within an hour (or very soon after).
HOWEVER, it's like ONE DAY for no reason, I completely stop getting daylight pictures, and the bucks show up less and less. Now these deer don't "rut" till at least Christmas, probably even into mid-January, but this cessation of daylight pics starts about late Oct. or early Nov. There are two things that are different: 1) I have begun setting in a treestand in there, and 2) the daylight period gets shorter. I fully believe #2 has a FAARRR greater affect on deer than most people know about. I think half the deer behavior stuff we attribute to hunting pressure is ACTUALLY caused by deer's internal, subconscious response to the photoperiod. Or perhaps it's something else like seasonal food pattern changes...the deer have moved farther away on a different food source, thus I'm not getting the visits at the same time now. I don't know for sure, but I don't think deer are as affected by me intruding as we think...at least not me simply walking in to check a camera, or sitting in a stand and not educating deer. (But I'm hyper sensitive to pressure, I think shooting guns and gutting deer and walking around KILLS your deer activity)
Yeah, I'm quoting myself, but I wanted to clarify what I wrote last because it sounds contradictory and muddy.
When I go in to check the camera I'm quick...I go straight to it, and right back out. I don't stand there and look at pics on a reader or stuff like that. I don't make a scouting loop. I'll usually tote a bag of corn in there by hand (I do NOT drive a 4wheeler in there). Now granted, I may do it after work sometimes, in work clothes with deodorant/hairspray/etc smell all over me. I'm not THAT careful honestly. For whatever reason that doesn't seem to alter the deer activity.
But in general, what I do above with cameras is quite the opposite of how I normally feel about pressure/scent. I'm really funny about that stuff, so it's kinda odd how careless I am with checking cameras (but again, that doesn't appear to scare the deer just judging by pictures). I believe PROLONGED presence in there--me sitting in there to hunt for several hours at once--and doing something other abnormal things is what spooks the deer. Not sure that just me occasionally walking through spooks the deer, heck other predators do it every day too. But me staying in there, shooting a LOUD BANG BANG gun, walking through the thick stuff, gutting deer, etc is what ruins the place.