See, the problem is you're interpreting words like "unlimited" by their dictionary definition.
You are pretty much guaranteed to get let go if you tried to do this without having a very good reason and a very understanding boss. Even though it is called "unlimited" that doesn't mean you actually get to take unlimited vacation.
So, it’s like “unlimited” Internet data plans.
The term my employer is using is "unaccrued".
Productivity is productivity. If you take so much time off that you aren't getting anything done, you're going to be fired.