marking coins is useless. Do volume and be consistent. I would advise against switching pickup locations, that's like changing your lotto pics every few weeks.
Coin Roll Hunting is really just luck and maximizing your chances to "seize an opportunity". If you want to add more pickup locations, I recommend increasing your bankroll, but continue to consistently search the banks you already do. You never know when that "little old lady" will dump her stash into circulation. If the turnaround time is 3 weeks +/- in your area, you could easily miss it by bouncing between banks for pickups.