I think we cannot keep doing the same thing for a long time, otherwise our concentration, focus and efficiency will decrease.
So during the weekend, I prefer to arrange multiple different things in a period of time, not simultaneously, just switch to another task when I get bored with what I'm doing right now. For example, after playing the piano for an hour, I would try to read a few pages of a book, or practice calligraphy for a while, that helps me refresh myself.
Moreover, the time that one person can work flat out each day is very limited (I mean in the flow state).
As a human being, after all, we are not like machines, it's unrealistic that expect us to work with high efficiency all day long.
Ironically, trying way too hard sometimes has the opposite effect. It's like I put an enormous pressure on myself every now and then, but the result turns out to be just the opposite of my wish.
So, as long as we can make progress every single day, that is still good.
"I am a slow walker, but I never walk backwards."