Over the course of the season, it does even out, but over the course of a game, it could favor one team more than another. I still don't think it's fair to the team that had to stop that play.
There used to be an unwritten rule where coaches would not substitue players during a no huddle and not allow the other team to do so. Not to gain an advantage by manipulating the no huddle and llast second substitutions. Mangini violated this against Indy and came under criticism for cheating from Dungy and other NFL people. They added the rule a few days after the INDY game to prevent the Jets from doing this again.
