How do sales centers' determine the minimum drop size for small format drops? Companies like PBG seem to have a minimum small format drop size for all their sales centers while others don't. Any reason why other companies do not?

The cost of getting product to the store plus the amount of stops per day a truck makes for the "minimum" quantity specs.
PBG has a higher min. case order in small format in larger areas than say a PBG in a rural area.
Smaller companies that sell niche products may see every order equally as importantant as the next in order to get their brand awareness out there and to increase volume.For them every case counts towards the bottom line while say a driver making a 5 cs drop in some areas will acually be losing money when you take into account gas, employee wages, truck Insurance, wear and tear,cost of goods sold, etc.

It depends on a lot of things -- probably geography and population density being the most important.

A friend used to run a c-store in a rural area -- she received bi-weekly (twice a month) drops. We have c-stores that receive 2-3 orders a week (Wawa).

greg is right -- the small guys rely on those small orders. To PBG or CCE, five cases is pretty marginal.

but when it's driver sell, they have to go to see what they need. a lot of PBG in michigan is driver sold, so they go to all of their stops in a given week, or just load them up one week once they know how much the store will sell in two weeks.