In practice… 1.
With the difficulty settings I play on, playing more than one character in a way that wouldn’t just be inheriting the items of the previous character would end up just disappointing anyway.
Most of the characters I like to play have a really difficult start, and a difficult time, even later on, but they need to advance and do things for about a week before they are interesting. And in order to avoid running into places that have been changed, before they have actually been changed, you need to advance multiple characters, one character at a time.
But it is hard for me to put a character down when something interesting is happening.