Good point. I found if I did forty the first two days, I could do 90 the third, and that is about as much as I do on an average day. When I first did it, I had only probably done 40 a few times and maybe never 90. And I had a lot of injuries to deal with. The thing I find works is to pace yourself entirely on comfort, stop to deal with any hot spots, adjust the saddle, apply peneton, etc... If one is so pressed to prove one can do a century the first day, then one might create a problem the first day out that leads to pain for the rest of the trip. I go solo, and would love to go with my wife etc... I think that would work, but I know I ramp it up the moment I fall in with someone else. I'm competitive, but given my injuries, I have the wisdom these days to insist I am only going at my own pace, but I can sure see why that would not be to everyone else's taste.