If a kid signed up/tried out/whatevered for a team because they wanted to play, they should finish the season. If they want to do jiu-jitsu/Taekwondo/whatever and their parents sign them up to a 6-month contract, they should finish the six months. If the kid wants to play Chutes and Ladders, they should finish the game no matter how many chutes they have to slide down. A kid shouldn't be allowed to quit when things are difficult or boring. Lots of things in life are difficult or boring, but they still need to be finished.