You probably want to take this with a grain of salt, given that I got my backside cooked on my century attempt, but I still think that to a certain extent, it was a matter of not selecting the right century and factors otherwise beyond my control.

I did a spin class on Monday (or did DIY spin on Tuesday), tried to get an outside ride on Thursday (20-25 miles), and then I had the long training ride on Saturday. Others did something similar, and they DID finish their planned centuries. The advice given was to push it as hard as you could on the short rides during the week.

And you can cook something in a crock pot for your mid-week ride day.