KotS is a full-on dungeon grind and really nothing else. The party could, I suppose, choose to approach it in stages - go in, clear out another dozen rooms, leave and rest; lather, rinse, repeat - but the adventure's backstory (such as it is, it's not great) assumes you'll go in and blast through it pretty much in one go, reaching the end encounter in time to stop a particular event from occurring.
Regardless, the end point I'm trying to get at is that no single adventure should bump a character more than once unless your intent as DM is that the campaign only be about 6-10 adventures long (in other words, much as a published AP would have it) from first level to whatever the system assumes the maximum is. To me, at the 6-10 adventure point a campaign is just nicely getting started: a few star characters are starting to rise above the rabble, various plotlines are either underway or being hinted at for later, and both characters and players have learned their way around the local bits of the game world.
Of course by this point my campaigns would likely also have multiple interweaving parties, all sorts of character turnover, rivalries-friendships-romances-jealousies within the parties, and so forth.
Lan-"sometimes the actual adventure finds itself buried pretty deep in the background of play"-efan