I think that the idea of erasing schemes in turn is not ideal, because the players analyze each other before the game and, first of all, the players will exclude schemes in which their opponent is clearly strong, so some mediocre nonsense will remain in the list, and not something that pleases both players.
I propose to modernize this idea: Before starting to erase schemes one by one - the players choose one scheme that cannot be deleted, and then erase the unwanted schemes. This will keep both players interested in the upcoming games.
But still it is not correct to deprive players of the game in the schemes they want, so I also adhere to the idea of simply increasing the number of games, for example, BO9 will be optimal if we take into account the number of schemes in TFL.
I think we should reduce the amount of schemes in Free League before trying any of these changes. There are so many schemes in Free League right now that you can hardly be bothered to master (or learn at least) all of them, and there is almost no incentive for a person to play the league if your opponent can just pick a scheme you have never seen in your life. I don't even know, for example, if Pro is in Free League anymore, or if Big RR is in Classic or Free; heck, people can't even remember Holy War rules anymore.
Right now, there are 19 schemes in Free League. What about we reduce it to 12? Then, each person would be able to ban 2 schemes, you'd have a pool of 8 schemes. We should open a poll, maybe? So these schemes are decided by activity and not niche pickers.
(Also, completely off topic, what about opening a poll to remove donkeys in T17?)