I agree! It's good to take at least one complete day off per week if not two. And taking time to reflect, or even leaving large unscheduled blocks of time in your schedule to think, strategize, reflect, or to do something else entirely is wise.
You are right in that I have many responsibilities, but I do find it's all doable in 8 hours per day. Up until recently I was only working 4 to 6 hours per day, but I found I couldn't quite get around to key tasks.
I've made weekends a little easier on myself in that I publish weekly digests on Saturday and the minutes from planning sessions on Sunday.
So, it's definitely possible to work ahead, and in general, I do.
I've certainly experienced burnout, as recent as September. I'm much better now. But it seems like there are many stages to recovery, and right now, I'm trying to work on my sleep.
Suffice it to say I can't let it get to that level anymore. Recovery was unpleasant, though much needed.