...In which case though, it does leave me wondering why we routinely go back for the penalty for an infringement closer to the goal line when teams fail to score even though they have gained territory and had the freedom to play as they wished?
Again, my stance is a territorial advantage
was gained in the original scenario you described. For an infringement close to the goal line, it wouldn't be possible to gain a territorial advantage. It would depend how close to the goal line the infringement occurred, for me, because I usually am looking for territorial advantage being gained.
Tactical advantage is less common IMO. Only things like an up and over kick to a winger on an empty side of the field where he has no defenders ahead / in front of him, etc, is a tactical kind of advantage to me.
For territorial advantage, I'm typically happy if the attacking team has gained at least roughly 10 meters while advancing the ball. It's never going to be exact, but I feel that's justifiably at least as advantageous as if they didn't use the advantage and went back to the mark of the penalty (where the defending team would've had to retreat 10 meters from anyway).
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I can appreciate the perspective between you and crossref in the last few replies that since the infringement occurred after time was over, and we know that a game can't end on a penalty but apparently can end on advantage being gained - even if not successfully used, that they might've been better off not taking their advantage and just going straight to the penalty.
But my counter to that is going straight to the PK doesn't necessarily mean they were better off either. Imagine they elected to kick for touch and missed, the defending team scoops up the ball and kicks it out, ending the game. Or they elected to kick for points, misses, goes out the back, game over. There are no do-overs in any of these cases. There's a multitude of scenarios where using the advantage may have put them in a better opportunity to score than taking the PK.