Parents can often tout the wonders of what a soothing car or stroller ride can do for their little ones, but if they're really ready to drop to just one nap per day, Spivack explains that those just won't cut it anymore. "Usually, we can still milk that second nap with the tried-and-true stroller or car — but when a child won't even snooze there, then it's time to drop it," she said.