Resting has no real consequences or roadbumps to stop you from spamming it. At worst you can just fast travel to a place you can rest no doubt. I basically didn't use any short rests in my 2nd playthrough and just used long rests all the time.
Got to the druid grove after 8ish long rests. Did a long rest after fight. 9 long rests in. Took my character 9 days to get there with 0 consequence I suppose.
Probably a couple of months before I got to underdark.
I can see a resource being days you have. Which makes sense thematically and discourages long rest spam. While leaving it up to you when you can use it. It makes sense, is thematic and up to you the player. Right now it's just free healing.