According to the wiki (http://pillarsofeternity.gamepedia.com/Rest), PoE has at least a couple of locations available for free rest. However, is it always possible to return to these locations from any point in the game? For example, are there any dungeons from which you can't leave once your party enters, forcing you to use camping supplies for rest?
If backtracking is always feasible, then the only gateway for potentially resting after every encounter is your patience, rendering camp supply limitations in higher levels of difficulty moot. Needless to say, this issue has a great impact on optimal party selection, so I'd love to hear feedback from those of you who are deep into the game.