Depends on the work culture certainly. Unlimited is, if course, not really unlimited. But whether (for a good performer) it's culturally 2 weeks or 6 weeks matters a lot. Even in an old-fashioned regular PTO company, I had people--though not my managers--incredulous that I would take 4 weeks of out-of-contact time.

More recently, someone I know who worked at a well-known unlimited PTO company told me that a newly hired head of corporate communications quit in short order because the CEO would actually go radio silence on vacation and they couldn't deal with that.