… Also, sometimes it comes up early in the game, and someone is stuck not getting to drink for quite a while until the game ends.

A: Switch To Water is mostly meant to be a way to make someone slow down their drinking for a bit if they’re getting a little too drunk. When to have that person stop drinking water instead of alcohol, or even whether to apply it in the first place can be considered subject to group consensus.

The card says “If anyone feels that a player is ’too drunk,’ that player must switch to drinking water” (emphasis added), so if it comes up early in the game, you don’t have to make anyone switch to water at all, if nobody is really very drunk.