There is a belief that to stop injuries it is best to stretch or do a little training within an hour or so of a game.

Maybe that person believes this, but instead of doing training decides that a friendly match, with a heavy rotation of players is better?

I have done the same before when I only had one game a day, as the extra bonus packs give me something extra too. I wouldn't do it if I had more than one competitive match a day however.