100mi/week and I have more strength for weekend rides now than before I started commuting just because I am in better shape. I don't get to do as many rides as I would like due to family responsibilities, but I did a 200km rando ride a few weeks ago. If I can figure out how to keep my knee from hurting, I'll make it a 300k next time.
The hardest part is not having energy for long rides after commuting, but have energy to commute Monday after a long weekend ride.