You make some excellent points and I see what you mean concerning efforts like VO2 max, but if a VO2 max effort is say, 110 percent FTP and I'm feeling terrible and decide to drop it by 10% I'm at 99% FTP which basically turns the interval into FTP training. Would this still be preferable for these types of intervals instead of a break? Or would you be more likely to only drop the intensity by a figure like 7-8% and add a small (say 30 second) break to ensure it stays in the "VO2 max" range?