The right outcome is more important here. How many times have we gotten screwed by bad umping? Are you saying that should just continue? I really don't see what the problem is with getting the right call. Why not let the better team win that day, instead of maybe losing because of a blown call? I say give each team 2 challenges per game, and the reviews will only last 90 seconds. That could get the right outcome as well as not lengthen the game by any significant amount of time.