Before I go into quote and response mode, I think we just need to clarify two things:
1) Is it your position that when the text says LTH can be "any color you choose", it is just fluffy set-dressing? It is there so MUs/Wizards can have a conversation with other PCs about "what a lovely shade of < > my LTH is, don't you think!" (not sarcasm there, just a potential example off the top of my head) Therefore, it is not an actual input to some form of action resolution to determine discovery; in AD&D1e this would mean affecting random encounter chance, while in 3.x and 5e, this would mean Spellcraft/Arcana vs Spot/Perception contest?
2) I saw you used the term "house rule." AD&D is basically the original "rulings not rules" edition (hence why 5e is a throwback). This is because so much of the rules are either (a) silent and requiring extrapolation, (b) directly at odds (incoherent), or (c) at least at tension. All AD&D games are basically a combination of hard rules and cobbled extrapolations. All we can do is discuss the nature of that marriage.
Do you disagree with that?
That one is even worse though, except for the shorter casting time. "Missiles, weapons, and most spell effects can pass through the hut without affecting it, although the occupants cannot be seen from outside the hut (they have total concealment)."
Here is where it is good:
a) It is a 3rd level spell.
b) It grants Total Concealment to the PCs inside. This is much more powerful than the -4 to hit that enemies get for attacking PCs (AD&D) in LTH because they cannot see them due to its opacity (another benefit of LTH).
Total Concealment in 3.x equals in independent 50 % miss chance! Roll to hit. Oh you do? Ok, now roll your 50 % miss chance!
c) Unrelated to the Secure Shelter comparison, but a comparison to AD&D Wizards; 3.x Wizards will have
considerably more spell than their prior edition counterparts and their saving throws scale in the opposite direction (which won't affect this spell, but just general info); saving throw DCs scale (significantly with magic items/feats) better than PC/enemy saving throws (ratther than the inverse in AD&D).
I'm not sure what edition you're discussing here, but in AD&D, it could take a magic-user a lot longer than eight hours to recover from adventuring. Eight hours was the minimum amount of time you had to rest before you could even start memorizing spells again--it could easily take another eight hours to finish memorizing everything--and of course anyone who'd hit Death's Door was out of it for a long period of time (a day? a week? I forget).
Edit: correction. I think in AD&D 1E, you could memorize some low-level spells after only four hours of sleep; eight hour minimum was only for 2nd edition.
Yes. The 8th level MU I cited would need 6 + 1 (15 minutes *4) hours to rest/prepare spells. So the 8 hours they get for LTH duration would be more than sufficient.
Sure, it helps you avoid foraging for shelter. I'm less munchkin nowadays so I could see myself casting it just because comfort is nice and the opportunity cost is low (similar to how I learn to create characters with Prestidigitation in 5E even though being warm and dry and having yummy food it has little mechanical effect); but both the AD&D version and apparently the 3E version are convenience spells, kind of like a cantrip.
Yep. It does what it says on the tin. Gives you a place to rest.
I don't see any indication at all in the link you sent me that it prevents combat. Enemies can see the "unmoving, opaque sphere of force of any color you desire around yourself" and "missiles, weapons, and most spell effects can pass through the hut without affecting it". That's not even close to being invisible, and it's not much protection either.
It's basically a gigantic magical umbrella, of any color you choose.
I'm lumping this all together. Ok, what I find relevant to the conversation (and clarification):
* Enemies attacking into LTH cannot see them due to its opacity. Consequently, they suffer -4 to hit the PCs inside the LTH in AD&D, 50 % miss chance in 3.x (and allowing Rogues to SA), and heavily obscured in 5e (thus Disadv to hit PCs and possibly Adv for PCs to hit enemies if you rule that way).
* Casting LTH saves PCs from having to deal with (i) exposure from the elements and exposure to Fatigue due to the number of turns they have to spend doing work that requires exertion (both of which cause them negatives to ability scores which requires rest to remove). (ii) Then they would have the chance for random encounters while doing so (exacerbated if they prolong the effort by spending the necessary turns to rest for a reset to their "exertion-meter" rather than facing a Con check for Fatigue).
* Related to my (1) question at the very top. If you're in a bog, you've got a default random encounter check every 4 hours (1 in 10, 12, or 20). Is it your position that PCs in a copse of trees who have made all kinds of racket setting up a natural shelter and have an exposed fire going should have the same random encounter check as the same group in a fully dark (sans racket and time) LTH in those same copse of trees?
I assume that is not your position? If it is not, then what other system machinery are you going to use in AD&D to resolve this if not the random encounter check die and then dismissing nonsensical results on the random encounter table (should the random encounter check yield an encounter)?