I read your comment and Barry Fry using 3 subs all at once, sometimes relatively early in games sprang to mind. I am sure it worked at times but also would have put the team at risk of getting an injury and being down to 10 menI often think bringing on too many subs can disturb the rhythm and flow of the team particularly if they are in the lead. We have all seen in friendlies how that happens.
MA used to tinker with the team near the end of the game for no obvious reason and often without a positive outcome.
Which is why I think clubs will use more than the normal 1 or 2 with caution, making wholesale changes near the end could lead to disaster.