I am so tired of hearing about "unlimited" vacation as if this is some revolutionary idea for improving employee morale. This intentionally blurs expectations and puts the burden on the employee to try to figure out the hidden acceptable number of days they can take before being viewed as simply "adequate."
And it could all be avoided if the company would simply define a number so expectations are crystal clear. Simple. Instead, what happens, is it becomes an internal competition to see how few days you can take and creates a very toxic atmosphere where people are judged based on the days they take.
Companies should be setting a static number of days/hours and encouraging their employees to take ALL of those days off, or at the very least, pay them out or roll them over if they don't use them.