That's been 100% my experience as well. The real choice for me is "do I want to sit in front of my keyboarding spiraling down further and being mostly useless (and feeling guilty about that), or do I want to spend a little time addressing the problem and come back when I can function." Often times even just 3-4 hours is enough to do that. Getting FMLA protection for my chronic health condition has been amazing for that as it removed the guilt I used to feel about taking time, and I'm more productive than I've been in years despite taking a few hours a week. Recovering from burnout is seriously hard and it honestly needs it's own DSM diagnosis at this point.