My daughter did the 18ish mile out and back to Owl's Head hike. She reached the summit and was chatting with a group of old timers. They chastised her for leaving the trailhead at 8 am, instead of 6 am like they did, and questioned if she'd have time to get back before dark.
Let that sink in, she left two hours after they did, and arrived at the summit at the same time. That's two hours faster over 9 miles...They were all heading back to the trailhead at the same time, and they were worried that she'd arrive back at the trailhead after dark, because she recklessly started so late in the morning.