Doesn't work.
Points 1 and 2... This would result in more wasted time, not less. You'd have basically at least 6 reviews per game, as towards the end why wouldn't a manager just appeal on the off chance something is spotted. These won't be quick, first the controller needs to decide what to show, then the ref needs to watch all these replays to come to a decision. before making his way back to the field... 6 times...
Point 3... This will drive people mad. A wrong decision will stand/be given as the ref couldn't decide within 2 minutes. All people will say is it was obvious, just the ref wasn't good enough to make his mind up quickly enough. This will add huge pressure on refs to come to quick decisions.
Point 4... the best one and better than the current system. I would still hate this as we shouldn't be giving offsides for a kneecap being 2 inches offside. Level should mean level within reason.
Very true.. thats why I prefer old linos making the decision.
But to be fair... and to add context to all of the above... I'm hugely bias. I hate VAR and want rid of it. So take all my comments with a pinch of salt.