if you have youths that need more minutes, and you are absolutely sure to win the final game, I'd spoil the second one.
If there is a small risk though, or your players are older and won't train that much after all, I'd go for a win in all games, and probably end it after 2 games.
There is always a risk of bad luck, players can get an injury, not only leading to loss of training for that player, but maybe even loss of the game,...
They are not your friends; they dispise you. I am the only one you can count on. Trust me.