I am not an optometrist, but I say to go on an off day. If you get what you need when your eyes are at their “best”, you won’t get to the point of the eye fatigue.
I would say that the most important thing is that you tell your doctor about the problems you are having, and make sure that they are addressing your problem.
I just got a new prescription for my glasses. I have been in trifocals for several years to deal with this problem. (Hated the progressive lenses) Upper part for distance, mid part for computers, car speedometers, and things more than an arm’s length away, and lower for reading. I was having problems seeing my computer screen, it was annoying that I could not see the entire screen without a fuzzy part at the top and the bottom (I was having to lean closer to the screen and tip my head backwards to see with the reading part, or push my glasses up with my hand to look through the lower part… So, I talked to my good, listens to me doctor, and he ordered the middle part to be made 1 mm wider. And it has helped!