Having exactly one type of "operation staff" does make a lot of sense, the smaller the operation actually is.

It would be even better, if the scheduling would be something like a rotation which every staff member runs through, and which contains days off, days reserve, and where a sequence of jobs begin with the late shift, and then shift earlier every day to end with an early shift. Such a set up gives additional time of rest to the days off.

This would for one give maximum staff use flexibility, with a minimum of monotony for the staff.