I had this discussion recently while watching a heavily favored team play outfield players as keeper, the keepers as outfield players, and most everyone else at unaccustomed positions. FROM THE START. While I understand that approach, I would say that an injury to a player in an unaccustomed role might raise a few eyebrows.
I kind of prefer playing it straight, to a point. I'd use my starters in customary roles for 20-25 minutes, perhaps with some "restrictions," then lift them and let everyone else play the rest of the way. If I had any concern about the effort required from the starters, I'd run a light technical training session for perhaps 30 minutes before game warm-ups.
To go back to the original approach -- playing kids out of position -- I will say that both sides of a one-sided game took it in good spirits and appeared to be having fun. And as my fellow conversationalist pointed out, that's a good thing.
The coaches' and players' demeanor are central to the good spirit.
