The longest I went without studying during that whole time was 4 months. And that was because I had company for the holidays then jumped on a plan and flew cross country on a vacation.
I managed to study every day of my vacation but one, so I was good about that. I just stayed on East coast time and studied early before people woke up.
I didn't so much burnout as I did make it impossible for myself to study on certain days.
Oops, I "forgot" to bring my books home from the office. Or, Wow, now that I've drank this whole bottle of wine, I don't think can study at all.
I had a real hard time giving myself a day off, but I found certain excuses or rationalizations that had the same effect as a day off.