Why measure days in groups of seven?
It's an interesting question, since different cultures actually had "weeks" of different lengths.
It
probably stems from the fact that a 28-day lunar month divides by 7 (and your other options along those lines are really just having a 14 day week, a 4 day week, or a 2 day week).
The more interesting question might be why so much
else about how our time systems work is weird. Why are there 60 seconds in a minute, 60 minutes in an hour, 24-hours in a day? All of which (along with other stuff like there being 360 degrees in a circle) probably goes back to the fact that the Sumerians and Babylonians used a Base-12 math system. And all these assumptions about how things should be measured just got passed from culture to culture, forward in time, until we today just view all of it as being completely normal and the way things should be.
And attempts to change it wind up failing like when the French tried to use "Metric Time".
Damn if it isn't one bleak fucking setting.
The thing to always remember with cyberpunk as a genre is that it's basically future noir. Which means everything is going to be terrible, everyone's going to be corrupt, and no one is ever going to get a happily ever after.
If you go into it expecting that it can be really satisfying in its own way. But if someone doesn't like being sad it's a genre they should probably avoid. It's basically tragedy in the truest sense of the word - everyone's going to be destroyed by their own personal flaws, and every protagonist is going to end up dead or worse off than when they started.
Cyberpunk 2077 does it very, very well.
