My son's coach does it. Coaches 12's and 15's in the same org.
Practices are always back to back, so one team is leaving as the other comes in. (yes, he lives at the fields/cages)
One thing I really like is the interaction between the two teams. The older kids have come to act like "big brothers" to the younger ones, and many come early to their own practices to help out with the 12's. Both teams watch each others games when possible, etc.
When there's a conflict with games, he always stays with the younger team.
I think he's insane, but has been able to make it work
Practices are always back to back, so one team is leaving as the other comes in. (yes, he lives at the fields/cages)
One thing I really like is the interaction between the two teams. The older kids have come to act like "big brothers" to the younger ones, and many come early to their own practices to help out with the 12's. Both teams watch each others games when possible, etc.
When there's a conflict with games, he always stays with the younger team.
I think he's insane, but has been able to make it work