Can you describe the super intense work outs? I find that very interesting. Particularly, the effect of a workout could vary drastically based on intensity.
Here's an example of a 45 minute workout I do at home about every 4 days. I have very little equipment and no gym membership. If you truly go to failure on most of the sets you'll be wiped out after this and will need several days of recovery. I add weight or slow down the reps each workout. If I can't do more this time than last time I know I need more recovery time in between.
Squats: 3 seconds down 1 up: 3 sets of 6 or 8 (to failure) with 30 secs rest between. Weight as needed.
Pushups: 8 seconds down 1 up: 3 sets to failure with 30 secs rest between
Diamond pushups or narrow pushups (mainly for triceps): 3 sets to failure at 3 secs down 1 up.
Chinups: 3 sets to failure with 45 seconds rest between. On last rep grunt it out for 6-10 seconds trying with everything you've got.
Shoulder flys and/or presses: 3 sets to failure. Weight as needed to get failure in 6 or 8 reps.
Shoulder-chest cross-pulls: @ 25 per side with 20 lb.
Situps: 30 at 1 sec up 3 secs down.
Windshield wipers: 20 per side
Mountain Climbers: 50/side
Locked Arm Torso rotators (with exercise band): 10 per side
I vary some of the exercises from week to week to keep it interesting and challenging. I'd love to start going to a gym but for now this is what I've got. It is changing my body noticeably.
This really made a big difference in my fasting glucose levels and HbA1C. Not to mention the many other positive benefits of intense workouts.