I think, and again I don't have much experience yet with that side of BB, but I think that teams with particularly small rosters like B3 teams rely heavily on stamina.
With high enough stamina, the GS impacts of heavy minutes during the week are lessened as I understand it which means that the number of minutes that your stars can play during the week without losing GS increases. Then it would just be a matter of, if you can't start all your stars in every game, picking which games to start them in. Doctors with Massage speciality and also the Sports Psychologist staff member help players deal with heavy minute loads as well. I imagine some of the more competitive players have the impact of those staff members and of higher levels of stamina down to a science.
Cheers!