I guess the problem I have is that I have seen far to many refs raising the flag far too early when the ball is still 20 yards from the keeper and 10 yards in front of the offside player that could stop and not be called for an infraction, or the ball is 20 yards in front of the offside player and the keeper will clearly get there first. Too many refs are still stopping with the last defender and raising the flag far too early and indicating the restart is even with the last defender. If the offside player and keeper are 5 yards apart and moving at top speed, I would whistle for offside.
Referees need to use some common sense. What I would call in a 9v9 game I would probably not call in a B17 game. If I have an offside G16 player going after a ball headed toward the keeper and her teammate is running into the play, I am not going to whistle for offside until the offside player is within playing distance of the ball. A 16 y/o has far more control of their body and can avoid that keeper and knows that contact with the keeper will more than likely get her carded and injured. A 10 y/o does not have that control or experience so the whistle will get blown earlier.
The "rarely used gimmick play" you speak of is not as rare as you think. Over the first two weeks of league I have worked 18 games (12 boys games (3 B10 and 9 B15-19) and 6 girls games (G14-19)) and seen 7 teams (6 boys and 1 girls) use some type of Offside plays and some have been very effective and resulted in shots on goal or goals. All seven teams were Tier 1 teams and played some good soccer. Three of the coaches gave the referee crew a heads up prior to the game that they had set Offside plays and to please not flag the players early and follow the changes to Law 11. I also had at least a dozen coaches during this past summer's tournaments tell me they had set offide plays, so we (refs) did not flag the players too early.