And just to be clear, I currently work at Netflix.
The idea of unlimited is that it's not 14 days or 21days. Take as many as you honestly reasonable need to. Everyone's life is different, you might get sick, have a sick family member, have a new child. There might be things that come up that requires you to take time off without you having to grovel to your manager. If you also need to take time off for the good times, a wedding, a party, to go see a world cup, Olympic, whatever, do so. So long as you're contributing, not holding your team and peers back and your impact is constant.
p/s. I don't work for Netflix, but that's what I imagine anytime I hear "unlimited".
For what it's worth, the company I just started at is "flexible", but the average is around 25 days per year.