If he is randomly hitting a food plot then you must wait for him there and hope he shows up. That is his pattern, randomly hitting different spots.If he is mature he may be moving during midday to the plots or at night.
I know you know this but stay as scent free as possible.
Other than that find the does and maybe you can get him during the rut following one by your stand set up on doe hotspots.

Can you find old bigrubs? This may be a clue as to where he is traveling also. I have read that deer will make rubs on the same trees almost to the day from year to year.
Hope this helps. I have the same problem, so much food so much ground to cover, no distinct pattern.