Why not just use the systems already in place for 5E to enforce long rests, so you don't have players running around like robots who never sleep? A day/night cycle to outdoor areas would ne nice, not only for knowing the passage of time in game, but also to allow for more stealth gameplay with nightfall, as well as giving the party exhaustion if they don't take a long rest once every X hours in game time? It would also allow for mid-day camp scenes, and let people know that yes, time is indeed passing in the game every time you rest, so you could have hidden timers for events if people rest too frequently, like some DM's do to prevent players from just resting after every encounter. For example you rest too much, and when you get to the goblin stronghold, they've already killed their prisoners and are marching out for their next raid. Rest too much after that and the results of that raid are randomly determined via multiple dicerolls, even could have the results regarding the prisoners in the fort be determined by several dicerolls as well, in the background while you're camping and taking your sweet time.
Personally any time I feel like I'm being rushed, I always make a beeline for the objectives, even when I'm not actually timed, so I was getting myself into a lot of difficult fights early on, however I still make sure not to use my resources frivolously, unless I'm planning on camping shortly. I usually only camp when it 'feels' right, meaning after enough events/fights have passed that I feel like could be done in a day, though that is immensely hard to determine without a day/night cycle represented. Do think you should be able to take multiple short rests between long rests though. It's kind of penalizing classes like Warlock and the martial classes because while they do benefit from long rests the same as the other classes, they don't *need* to take a long rest to recover their stuff, depending on their sub-type in some cases.
