Have you traveled without going by the TouringPlans guidelines? I ask only because even on the busiest of days, you can usually work everything in by going to the parks early, leaving during the middle of the day for lunch, then returning in the late afternoon and evening for more fun. Combined with using fast passes as much as you can, plus some plans like trying the popular rides during parades or fireworks shows, etc., you can get everything done.
We have been at WDW on Christmas Day, Thanksgiving Day, etc… and we have marvelled at how some parks have very light crowds on those days if we go early - we’ve had some crazy deserted holidays at all the parks when they had high cowd ratings. And lately, over the past 5 years or so, I have seen that the big attractions are often crowded but the rest of the park areas have light crowds.
I know TouringPlans can be a nice guideline, but it’s still guesswork and I have seen them be really way off the mark. I think you will be fine if you just go ahead and plan to be at any park on any day. Keep us posted!