I answered Adults at least 50% of the time.
While 228 usually has a college or adult mentor with extensive experience on the field to fill in the role of FRC drive team coach during the competition season (which includes any regionals, Championships, and BattleCry@WPI
), there are sometimes exceptions. Generally, the students on the team want to win at these events, so the team will pick whoever is best qualified for the positions on the drive team.
But once we get into the rest of the off-season, we usually mix up the drive team and let as many students as possible have some time on the field; and that can include student drive team coaches. At these events, the students don't care as much about winning as just having fun out on the playing field.
And our Vex team(s) have always been all students for everything.