Welcome to Flyertalk.
Never apologize for asking a question, Mileage Runs are a very confusing beast, which I don't think can ever be fully understood.
Do you usually find better MR from the small or large airports?
My answer would be Yes.
It's going to depend on what the airports are, and where they are. If the small airport mostly serves business people Monday through Friday, but has nobody on Weekends, you may find some great weekend deals.
If the large airport is a hub airport, you may never find any great deals there.
It also depends on what competition, if any, there is at the small airports. If it's served by only one carrier, there's probably less of a chance of finding deals then if there are three carriers that will price match should one lower their fares.
I would always check everything, you may see a pattern where the smaller ones work better, you may not, but you never know when something may pop up.