That’s a very interesting approach. It reminds me a little of the Bulgarian system for weightlifters, except that they used not only high intensity but also a high training volume. And it only worked for very talented people who, on top of that, didn’t work and basically only trained.
What I like about this approach is that if you enjoy working with heavy weights and don’t like exhausting high-rep sets, then it obviously makes training mentally easier. You’ll actually enjoy these workouts.
On the other hand, constantly working at 90% puts a lot of fatigue on the CNS and a lot of stress on the joints and connective tissues. Very few people can handle that, and even high doses of steroids won’t change much here. Also, if you were 20 years old, this approach would have a better chance of working well.
If I were using this system, I would change a few things. First, I would completely remove this approach from every exercise except the squat, deadlift, and bench press. I’d do all the other exercises in a more traditional bodybuilding style with higher reps, or use cluster sets, for example sets of 6 reps. Or something like two sets to failure for 10–12 reps.
As for the main lifts where I would use this approach, I would definitely add some load cycling. For example, one week following this plan and the next week being light. What does “light” mean? There’s also a lot of room for experimentation here. It could be 1–2 sets of 10 reps at RIR 0–3, or for example 3 sets of 5 at RIR 4–5. There are many options, but each one needs to be tested and the results evaluated after a few months.
In any case, I would start changing something if you feel that your progress has stalled.