I know Icelyn. I had you in mind when I said that this isn't a timed quest suggestion.
I also don't want to be locked out of quests because of taking too many long rests.
What I don't want and agree with you on: You meet Ethel. You don't go to the forest path heading towards the bog. You don't get to do any of the Hag quest events at all because you did several long rests and didn't go towards the bog until like day 3 or 4. Well. Guess you have to start over and play from the beginning if you want to play the hag quest stuff.
What I do want: You meet Ethel. Regardless of when you go to the forest, Ethel is there with the two guys. Things play out. Dang! After the fight with the hag and the redcaps, you need to long rest. You long rest and find that the bodies are all gone.
If you went into the lair immediately, things would play out as they do now. If you long rested, the hag taunts you. "Needed a bit of a rest after that first bout, eh? Were ya tired, Precious? That's okay. I knew you'd be back, and I've been waitin' for ya. I'm actually quite grateful. Ya gave me time to properly prepare for ya. Now we're REALLY going to have a lot of fun." Then she cackles and vanishes.
You proceed into the lair as normal except maybe there's an extra trap or two or encounter or something fun to show a difference between going in right away and long resting. The hag had more time to prepare, so now there's something more that you have to do. It's not locking you out of the quest. It's adding flavor and showing that your action effects the world in the game. You chose to long rest, so something different happens. Nothing big, mind you. Just something to show a variation in paths.
An RPG is like a Choose-Your-Own-Adventure. Each choice you make should have some varying path that you take, and that should include long rests. The path doesn't have to, and shouldn't lead to, a direct "Dead End", but it should have some sort of varying situations so that it shows that your choice made a difference. Otherwise, if my choice isn't going to effect anything, don't even give me a choice. Just have me do something and give me a valid reason as to why I did it. Don't give me a choice and then make that choice pointless, as if it really had no impact at all.
Right now, time and long rests have no real impact on the game. You might as well provide the characters with some sort of alternative full restore solution than long rest because taking a long rest doesn't impact the world in any way other than to fully heal you and restore your spell slots. So Larian might as well provide those nice mind flayer restoration pods like you have in the beginning, and have them everywhere so after every battle you can just tap on one and be fully healed.
That's the point many of us have been trying to make about long rests. Without some form of impact, you might as well just skip long resting altogether and have restoration chambers that people can endlessly use to recover to full strength. By not having long rest impact anything, it is pretty much the same thing.
Long Rest in Current BG3 = Mind Flayer Full Restore Pods. There is no game world impact.
