Short rest could maybe pass 1 cycle while long rest would go 2 cycles further. I'm not sure there's engine limitation for D/N cycle... But I'm close to sure that devs that want a D/N cycle in their game can be creative. It shouldn't be that hard, everyone has a D/N cycle, even games far less polished than BG3.
Night instance for quests would really suck. It looks cheaper than anything else to me... Especially if the night quests arrive after 50 hours without night gameplay.
I am not saying D/N is a bad thing, or it shouldn't be in the game. Honestly, I think it would be nice to have it. But it won't interfere with my playing or enjoying the game any less. I was just explaining to Sigi98, that depending on the engine, it can be complicated. Especially when it is a custom engine, where game engines like Unreal or Unity, they have HUGE staffs of engineers working on the next gen of their engine. Larian more than likely doesn't have that. The previous engines also have huge communities that make addons to sell, Larian doesn't have that.
A perfect example of engine limitation is SWTOR. They bought a license for the Hero engine, then edited so much, that even the engineers from the supplier couldn't help them update it. All their original engineers that edited the engine, are gone. Just a bunch of new kids working on it now. With, as the rumor goes, has very limited inline notes in the edits, which when you are coding is essential for future modification or even debugging. Now, the MMO is kind of screwed, they have reached a dead end where they cannot pass with their modded out Hero Engine (Hero engine sucks anyways, not sure why they chose it to begin with).
I mean look at the past, they even said they would like to have a D/N cycle as a stretch goal for DOS, never happened. They are using the same engine but a little juiced up, so logically, I am thinking this is an issue for them. Not to mention, the more content they put in the can, the harder it is to integrate it. That is something that is easier done before all the work they have put into the construction of the game. They even came out and straight up said "there will be no day/night cycle".
Personally, I rather think that given that history, it is more than likely a technical issue. Maybe they are working on it and will launch it as a surprise in live, or not. But it is just annoying when posters act as though game engines are this limitless thing that of COURSE can do it, they just...I don't know choose not to do as a big screw you? I mean does that even make sense? It would also be nice if people are going to make statements about game engine capabilities, I don't know, maybe have some experience working in a game engine.