What I have found works best for me and doesn't require a large bankroll is to open up accounts at several different banks. Preferably all reasonably close with multiple branches so you have some designated as pickup branches and others as dump branches. This allows you to coordinate a pickup and dump schedule that works for you.
Right now I have 3 major banks and a credit union. This has allowed me to have two boxes per day or up to 8 boxes in a single day if I choose.
Also, even having just two banks with multiple branches you can schedule multiple pickups through the week.
Spreading it around like can mean a lot of work going to different branches, which may not be an option in smaller areas. However, it is also less likely to blow a banking relationship as no bank branch will have more than 2 boxes a week.
HH!