Delaying the time you leave the house each morning by 30 minutes could save you 20 hours a year in commuting time, according to a new study looking at U.S. census data. Nationally, 3 in 5 Americans leave for work within the three-hour window of 6 a.m. and 9 a.m., according to Census Bureau data compiled by Yardi Kube, a coworking space management platform that coordinates flexible workspaces for businesses.