Concerning a five-minute(or even three-minute) round timer, I've always looked at it like this: when a team wins mid, they have earnt the right to push second or last, depending on how strongly they won the mid. However, if they keep banging their heads against the wall for five minutes(that's at least five opportunities to probe the point with über), you can give them one last "free" push that favours the attackers because they don't have to worry about getting run back, and then the round timer will reset. You could even make it so that as long as there's time on the point, there is overtime even if the round timer has hit zero already. If they really can't cap at that point, they've had a fair shot and they'll have to prove again that they really are the better team and play a new mid. Why should winning a single mid give you the power to stalemate for a third of the game clock? It's just one of the three different points on a 5CP map.