A big transgression umpires are missing are players going way over the mark to slow down the play. Watch how many point at a spot on the ground to indicate where they say the mark is - often it is 1-2m past where the mark should be. Umpires let them get away with it, simply trusting that because the players are pointing it must be where the mark is. It forces the kick taker back a couple of m and generally holds play up. Enough time for the moment to keep play moving to be missed. You watch any game and the amount of players pointing at the ground as they approach the mark has increased markedly. It's clearly a coached tactic. Umps have to get smarter and just pay the fifty. No warning. Get sick of them telling players who clearly know what they are doing to go back a metre. Often more than once. Just pay the fifty, players will stop doing it and the game will flow better.