Bacon Bits
Legend
There is nothing inherent in a sandbox that precludes an evolving world with time-lines (and, thus, potential time-constraints). A good sandbox will have NPCs with agendas - who will actively seek to advance those agendas.
The point is that there's no mandatory timeline in D&D, not that I can't imagine a campaign where one exists. The point is that it's possible to have a campaign structured like Minecraft rather than Final Fantasy XIII-3.
I just find it very irritating that so many DMs feel like it's acceptable to effectively railroad the PCs by putting a clock on everything? Why are DMs feeling the need to limit resting? Honestly, I still haven't seen a good reason to limit short rests. People keep saying, "Oh, just put the PCs on a clock. Just make the world keep moving without them." Yeah, that's how you can do it, but why is it so necessary to limit resting? It's not like the Warlock is going to rest 4 hours in a row and get 10 spells for one encounter or something. Are the adventure and promise of XP and treasure not compelling enough for your campaigns? Are your short-rest characters obscenely overpowered or dominating play? Is the problem Leomund's Tiny Hut is makes resting too easy? What's the problem that short rests are causing?
It's not like there was no rest period in previous editions. Hell, in 4e, you got a short rest in 5 minutes. In 3.x, a short rest was however long it took to activate your wand of cure light wounds (or whatever) enough times to heal the party. We've been short resting for 15 years now, but that name or some other. Why is 5e's hour long rest throwing a wrench into your plans as a DM?
Is it just the fact that it's an hour? So drop the time limit! Make the duration of a short rest long enough to cool down, clean up, have a bite or a nap. Make it 5 minutes, or 30 minutes, or whatever. The time limit on a short rest is not the critical factor. The time limit is arbitrary. The important part of a short rest is that a) the player characters must be reasonably safe from attack, b) the player characters that rest are unable to do anything productive, and c) the NPCs are able to do things that are productive.