I have used all three methods but I had to vote for "natural trail movements" as that is what I have been focusing on more and more. This time of year I set my cameras on field edges just to... well honestly... just to get pictures. As the bucks start really showing what they will look like (usually early August) I will put out a bait pile for a few weeks to try and get an inventory on the deer in the area... a month before season all the bait piles are used up and the camera's are set-up to try to find patterns on where the deer are moving.
I voted for over bait piles. I put them near natural trails, but I typically put out a little corn as well just to give them a little more insintive to stop
I put them over bait piles for about 5 years now. This year I'm going to do some trails instead. Thae year the oldest deer I had on film was 3.5 so I know I missing some deer.
Mineral licks in the summer, fields in the spring (turkeys), scrapes during the fall and on trails any time in-between for me.
I chose over natural settings. However, occasionaly I will put a sandwich bag full of something to get them to stop for my picture. So I don't "consider this a pile" more like a few handfuls, but it is a little something for a smile!!!:d I personally consider a pile something like a 40 lb. bag of this deer attractant/corn or whatever...??? So, kind of a two part answer for your poll, I guess? Pretty much after season camera scouting only. I rarely use cameras during the season, unless something peaks my interest and @ this point I never put anything out...
That's the way to do it as far as I'm concerned. Putting cams on trails right now doesn't get you as many pics as the mineral licks do. I like watching them grow from week to week.
I have been using some good trail set ups right now. The trails I have been setting up my camera's have been trails on pinch points and wooded fingers. Think I may have found a well traveled trail as I have collected 53 pics on in it in two weeks. Only bad thing is I have yet to get a shooter buck. Have a few of these below