Every month or so I do a 118 mile fg ride w/85 GI and 5 cat 5 hills. What I do is take the Friday before and Monday after off of my regular 33 mile rt commute w/a 500 ft elevation drop into work and a 500 ft climb home. I work 2nd shift which means I'm pulling the meaty mileage in the cool of the evening. And yeah I end up doing switchbacks on some of the hills on the fg ride, but each time I do the ride I'm able to pull a bit more straight on.

Those weeks I do 132 commuting miles and 118 fg miles for a 250 mile week. The only downside is the length of time it takes. Sometimes, I'd rather be watching baseball, but when my vitals, and cholestral numbers, etc. come in it makes it all worth the sacrifice.