When I was doing freelance work I worked for ~4 hours every day of the week. I got much more work done that way than doing 9-5 Mon-Fri even though I was working less hours in total. Its a much easier rhythm to get into and you get to skip those unproductive hours spent just waiting for the clock.

This works especially well when you are doing creative work. Come in and do at least some work every single day you possibly can. You don't have to do a lot of work every day, but try to stop at a natural stopping point.

My theory is that by working every day you keep the work current and churning in the back of your mind; while by working to a natural stopping point, you avoid feeling frustrated by loose ends.

Good idea, but make the workdays of everyday shorter so you still get same amount of hours of work done each day. I much prefer this method since whatever you were working on is still fresh in your head.