What is stopping someone with an unlimited PTO schedule from planning 40 days off a year (setting aside holidays)?

That's just:

* 2 week (10 day) vacation in summer

* 3 week vacation in winter wrapped around Christmas and New Years (so let's say 12 work days off)

* one Friday off a month (12 days)

* slapping on 6 days around holiday weekends, or wrap a couple of long weekends around those Fridays off

40 days out of basically 240 scheduled work days seems reasonable enough.

What I really wish is every 2 or 3 years you earned a 3 month paid sabbatical to go chase your dreams or maybe even do skunkworks or shadow a leader in the org.

I also prefer this solution, although for me it's always looked like:

- 25 + 5 (must use 25, can collect arbitrarily) + 11 official holidays.

- The ones that can be collected can be paid out, the must-use ones cannot.

- Paying out collected days off at your current salary means you get more if you wait for a raise.

If I want more, I pay for it, and if I want less, I get paid more.