As an example, I just came back from two days of diving last Friday. I did four dives on the last day, two dives below 100 feet averaging 25 minutes bottom time and two shallow reefs averaging about one hour bottom time, starting at 9am and finishing at 4pm. My computer said to wait 14 hours and 30 minutes before flying. (I usually do only two morning dives on the last day, one deep and one shallow, and my computer usually says to wait around 10 or 11 hours.)