Years ago, I used to play by the game, and played 16 hours one time matched up and broke even. I swore to myself then I would not do it again because:
1) Playing that long at that time got me in trouble with my family.
2) I had nothing to show for it, and considered it a waste of my time.
3) When I play someone, it is a competition, not practice. I practice by
myself.
4) Tides change over time, and per game, someone can get you down, and quit after which game they decide to. Even if you get up, you have players that will quit when they get $30 down, but will play forever if they are up.
Playing sets, you:
1) Make more money (a priority of mine).
2) You can cut it off and give a one, two, three more set notice.
(which is agreed to or understood between you and your opponent).
3) To me, this is a more gentlemenly way to play. Even if you are stuck,
you are assured of having one, two, or three more sets for a chance to get your money back, and you can double up if both agree to.