Yeah, you don't get the thunderstorms and such that require an early summit. I actually find that waiting a bit in the east can help clear the fog and raise the temps more often than not.I guess most tourists don't get up very early. Compared to the summits I've done out west, ours was quite late (it was a tourist type thing afterall, not in a big park).
Mansfield is a fun climb. but a bit ridiculous at the top late in the day in season. When I was backpacking last summer, I stayed at Taft Lodge on Mansfield. I was amazed at how many people just drove up. I really couldn't believe it. People looked at me and said "wow, you walked up?". I was thinking "Wow, you drove up?" I didn't bother explaining that I walked there from Williamstown.