I've never tried to push it when riding a Century. Even 40+ years ago, when I was averaging ~500mi/wk, I don't think I ever did 100 miles in less than five hours, even in a group. Six hours of saddle time was always my goal, so maybe 6-1/2 total counting water/snack stops (even back then I only carried one water bottle). My longest day of ~130 miles (solo riding) was done in a tad over eight hours including food stops.