If company policy allows it, that's great. But some of us don't have the option of payout. In my company, any vacation time not used by the end of the year is forfeited.
There are plenty of opportunities to game the system. When we adopted my first son, my wife took her leave, then I took mine. I started leave on January 3rd, meaning I was at work on the 2nd, clicking the "he was here" bit in the system to give me vacation days at 1/12 year's worth. I returned on the last day of March, clicking another 1/12 year's worth. So even though I was essentially gone for 3 months, I only missed out on earning vacation time for one of those months. Company policy stated that if I worked for at least one day during the month, I received vacation accrual.