I hope it is not a mistake I will make again, but the one and only time a mark was called so far in any of my matches I missed it. Perhaps because the U15 who caught the ball fairly in his own 22 had no actual sound coming out of his mouth, male teenagers being known to have that problem at times. Players from both sides slowed down, but none of the players from the kicking side were very close to him, and the catcher's side was already out of sight in terms of scoreline.
The catcher realised I had not whistled before other players did, and went on to score from his own 22. In retrospect I should have whistled when he started running and others were acting befuddled, of course.
Fully agreed that any referee should whistle as soon as the mark is made; advantage is not an option.