We didn't track vacations at my last company, because we agreed with the Netflix principle of hiring the right employees and giving them a lot of freedom, including allowing them to take whatever vacation days they needed, whenever they needed it.

There were worries initially by some about employees abusing this policy, but that has not happened once in the 6+ years we've been around. However as we've grown, I strongly suspect that the opposite is happening, i.e. employees are not taking as much vacation as (I feel) they should, perhaps due to the feelings of guilt mentioned in the article. This sucks because, unlike jobs where vacation days are tracked, we can't even compensate them for any unused days.

So over time I've come to believe that unlimited vacations days is something that sounds good in theory but not so much in practice, especially as a company scales. I would instead recommend the traditional model of tracking vacation days, but with a very liberal number of days (vs. the typical measly 10 days a year or whatever).