On top of that, PP continues, "Combination pills work best when taken every day. Progestin-only pills must be taken at the same time every day." So if you're someone who doesn't like to play by the rules, you may want to reconsider when it comes to oral contraceptive.
If you don't follow your birth control directions to a T, they're not guaranteed to work. Same goes for forgetting to take them at the same time every day, or forgetting to take them completely, though if that happens you probably don't expect them to work at all.
Though antibiotics have likely been blamed for many an unplanned pregnancy, following your pill's instructions and triple-checking any medications you plan to take alongside your birth control can keep yourself free of diaper duty.