One of the main reasons why a day-night cycle is a problem to implement is the possibility of splitting the party, like I've said before.
In DOS1-2, and in BG3, it is possible for some characters to be in TB while others are not in combat but in RT exploration mode. Technically, time would be paused in TB, passing at 6 seconds per round. But at the same time many things can happen for other characters in RT, they can even travel the whole map and join in the fight, all in technically 6 seconds combat time. Time is highly abstracted there.
That's actually just Larian shooting themselves in the foot with a thermonuclear weapon.
I can see why they have done it like this and what they tried to achieve, but there is literally nothing good about this solution - inconsistent time, ability to do arbitrary amount of shit or movement in between turns if you are not participating (so escape combat, heal up, gather supplies, travel to advantageous position, reenter combat), etc.
What they should have done is making switch to turn-based mode global. One PC enters combat? It's TB time.
Party is split? Tough shit, maybe try to support your bros next time instead of derping around.