I took a month long break since finishing Insanity in which I just did a few workouts per week (mainly Fast&Furious and a couple of the Month 1 + a few spinervals). Resting pulse dropped suggesting some previous overtraining. BF% went back up a bit.
Last week I started on Insanity Max:30. So far so good. (My shoulders are DOMS killing me as I type this.)
In terms of intensity, this feels like month 3 in terms of stepping up similar to how month 2 felt compared to month 1 (see post above). The exercises are gnarlier (more stupid human tricks involving more motion/coordination, but I' getting used to picking them up faster); and there are practically no breaks. Post exercise soreness appears almost immediately after a few hours akin to clubbell or kettlebell density training. The good news is that workouts all only last 30 minutes which I greatly appreciate. Month 2 took almost one hour each every day ... which is a lot considering the HIIT nature---almost a 1000kcal total burn. Max:30 is just HIT... there aren't really any intervals left. Also, there's practically no stretching. The warmout is part of the workout and thus you just kinda scale into it.
In my opinion, this system works great until the point where one maxes out. After that it feels like efficiency goes down a lot because there are no 30 seconds to recover. Compare doing burpees for 3 minutes followed by a 30 second break and then repeating. You might last a few rounds. Then try just going all out until you fail. Then start again. The first run is great. The subsequent ones get more and more pathetic. Of course this pushes the body a lot more even if the total reps are ultimately fewer.
Interestingly, while Insanity was mainly limited (for me) by muscular endurance, Max:30 is mainly limited (for me) by aerobic capacity. Which is new, and weird, and pathetic. Also nonstrategic, since aerobic capacity is one of the few age-dependent markers
I'm happy to note that I'm somewhere in the middle of the cast this time. Last time, I was near the bottom when I began. Of course there are always a couple of superhero[in]es.