The idea seems so simple: Instead of carefully tracking how much time each employee takes off during the year, we all agree to treat one another as professional, responsible adults, and take off whatever time we need consistent with getting our work done. That’s the idea behind unlimited vacation or PTO policies, and it does seem great in theory. Employees get flexibility. Employers don’t have to book accrued vacation or PTO or worry themselves about complicated recordkeeping. Everyone is happy.