I first started hearing about it 20 years ago, and was able to confirm it for myself earlier this year. In order to truly de-stress, to let go, you need 3 weeks away. Doesn't have to be a 3 week vacation, just 3 weeks of not thinking about work.

If you can do it, I highly recommend it if for no other reason to clearly see just how much stress your work is adding to your life, even if everything seems "fine".

I say that fully acknowledging that very, very few people will get that opportunity, "unlimited" PTO or otherwise.