Time rules are terrible and this should be an optional rule not enforced on ladders at most. Speaking from someone who plays a game with
absolutely terrible time rules, nothing is more infuriating than getting into a grind game where you're in a winning position and the time rules ruin you because of an arbitrary condition that fails to take into account the context of the game being played. Time rules end up encouraging faster play that can result in uninformed decisions being made that otherwise would not occur, as well as
actually stalling to achieve the "more Pokemon = win" condition rather than play to beat them, at least when the time is running around halfway in. These are always proposed by people who get mad at slow or "campy" play and then they realise that "play lame win games" is and always will be the
most
effective
tactic
available, and get mad at themselves losing.
If you wanted to implement this right, it would probably come down to what you're proposing, but with an "end the current turn before time is called" clause. Even then, these are generally a very bad idea and punish legitimate strategies with regards to outresourcing your opponent before opening them up for a sweep.
I think these are well-suited for casual play, but the minute you put them into a competitive sphere, you can and will get the opposite of what you want. Besides, who doesn't like seeing some guy call everyone in Lobby into a game going on for 500+ turns? It's hilarious.
EDIT: You could argue this helps with VGC accuracy given the cartridge runs a timer, but I would still be opposed to usage on ladder specifically as it's often used for field testing and learning teams before committing to breeding and whatnot. Thus, you wouldn't impact your in-game rating over having to think too much about your moves, etc, which is normally improved over time through building your schemas via said testing, etc. I haven't worded this well, but you get me, right?