Let's face it, in current IGC rules sticking to the gaggle is a very efficient strategy. Consistent (and well executed) leaching is usually not enough to get you onto the podium, but it's a cheap ticket to a nice and comfy place in the top quartile. Even the really good pilots need to "work" with the gaggle to fence their risks, especially on difficult days.

In my opinion there are three good ways of addressing the issue:

1. A few years back there was an experiment with a software which would retrospectively score competitions on leaching/gaggle flying. Any pilot entering a thermal after the first four entrants would score leaching points. At the end of the day the points would be aggregated leading to a leaching ranking. The ranking worked very very well and nicely showed which pilots made gaggle flying their strategy.

Setting this kind of algorithm up to generate penalty points would be pretty easy. There could be thresholds to tolerate some level of gaggle flying. The penalties should be kept as small as possible - just to make a consistent gaggle strategy to expensive to be economical.

2. The start game is one of the most annoying parts of competition soaring. I really can't imagine who actually enjoys waiting around the airfield forever before starting the race. Unfortunately, on many days, you need to play the game to not lose out.

There are lot's of ideas on how to improve this situation. I like predeclared start times where each participant gets to declare three starting time relative
to the gate opening. For example, you predeclare (in secret) that you will start either 10 minutes or 25 minutes or 38 minutes after gate opening. That leaves enough room for making your own choices but makes it a lot more difficult to leach off the good guys.

3. Change the scoring formula so that fencing risks becomes a less of a winning strategy. Today you get no reward for being the lone finisher and are heavily
penalized for being the lone outlander. The scoring formula heavily incentivizes sticking to the gaggle. There are plenty of ways to change this.