I'd say that the expectation is that everyone work "full time" on the settlement, maybe converting silver cost to labor hours at the standard unskilled/skilled labor rate or something like that. For this type of endeavor, it would probably be "work or starve". Adventuring would be different as the dangers of doing so are far higher than stuff like digging wells, raising palisades, what have you.
Also, what is your philosophy on rolling checks? Some GMs like to have people roll only when they request, others encourage preemptive rolling when the PC tries to do something that might have a chance of failure.