That's no good for people who have interests outside of the office. For example, I have two young boys and I want to spend my time with them on a Friday, not in the office.
It makes some kind of sense: boxing the time for creativity ends up killing it.
John Cleese argues the opposite: https://www.youtube.com/watch?v=VShmtsLhkQg
From the rest of your comment, it seems to me that the feeling that it's a chore might be more the reason it kills creativity - not the setting aside time in and of itself. If you don't look forward to that time (not saying that's a bad thing, one way or the other), you probably won't get much out of it.