Currently running Curse of Strahd. I want my monsters and world to be deadly, particularly because I pitched it that way and because it'll challenge my players.

However, from what I've seen and heard, character death plays out in one of two ways: 1) The other characters force a companionship with the new character, in a sort of meta-game fashion to keep the game going, or 2) the game slows down for the party to find this new character, or adopt them into the party.

This gets especially problematic in dungeons and such, where the likelihood of finding some random stranger/character is very unlikely.

How do you handle stuff like this?