One shouldn’t work every day. You should try to improve every day, but whatever it is you do for a living, make sure you take a break.
This gives you the dual advantage of being able to concentrate on other things, and also being able to come back to work in a more focused manner once you decide to.
The weekend is an obvious time to take a break.
However, you should approach work in such a way that taking a break is not mandatory, but pleasurable in its own way.
Because we will spend a large part of our lives working, make sure the work you do is something that you can be passionate about.