SetsulHigher time limit -> teams will park the bus because they don't have to push.
Lower time limit -> teams will park the bus because they can wait for the time to run out.
Now some have concluded that this means any deviation from <current time limit of their choice> will result in an immediate and irreversible public transport apocalypse where busses rule the world and everyone is too afraid to even leave spawn.
Others might say that apparently the team that is ahead can and will park the bus regardless of the time limit if that's what they want to do.
in the current NA system teams are more than capable of parking the bus, but theres so much time that if you do want to park the bus you're gonna have to wait a LONG time. everytime that i'm up in a game now, if theres less than 20 minutes left in the second half then i'm more than fine to park the bus for that whole 20 minutes, but that rarely ever happens.
IMO the real advantage in stalemating out isn't that you're going to win off time, its that it puts incredible amounts of pressure on the other team. it forces them to try things that they wouldn't otherwise, and they have to take risks. the higher skill level you get, the easier it is to punish teams trying to take these risks.
when you lower the round timer, teams don't feel that pressure as strongly. if you want to wait the current 10 minutes for a round reset, you're going to have to endure 10 minutes of whatever low % plays and nonsense each team goes for, and if you run a sniper for 10 minutes no matter how bad they are eventually they'll headshot something. If you kill a demoman defending last and you're down and theres 6 minutes left in the round timer, you'll be pretty willing to push out. If the same thing happens and you're defending last, when you headshot the other teams demo and theres only 1 minute left in the round timer, why risk pushing out? in 1 minute the round resets and you basically get to push out of last and second for free and get another mid fight
i don't think that any of the parking the bus problems are actual problems until you get into invite games where people care about winning more than the fun they're having, i don't think any open/most IM teams will be regularly parking the bus if we go to etf2l's ruleset, unless theres a few minutes left. No matter what ruleset we play, if there are sub 5 minutes left in the game and you're up rounds theres almost no reason to not slow the game down and force the other team to try and make things happen. this is just a fault with tf2, and i don't think theres any easy way to remedy it.