I'm still on the Buff Brides workout plan, and I give myself a D for week 12: I wasn't home on Monday, so I worked out Tuesday and Wednesday. I thought it might be a bad idea when I did it, which was confirmed yesterday when I was a big ball of soreness, and further confirmed today now that all of my muscles are SCREAMING. So I will be missing today's workout. Ahem.
But other than missing one Friday workout in week 6, I've been totally on top of this workout plan and haven't missed a single session (except the cardioI am way behind on cardio). I think one missed workout every six weeks is forgivable. Next week switches from three to four days a week of weight lifting, though, so we'll see how it goes.