The original broadcast version of BS Zelda used the actual current time, it was was broadcast at 6:00 pm so the timer in the game said 18:00, it had four weeks and each week was playable for around an hour. So the total play time was almost 4 hours. There are different rom hacks of the game and they handle the time differently, lots of them start at 00:00 instead of 18:00.
Here is a faq on one versions clock
https://bszelda.zeldalegends.net/bs1cheats/time.txt