I think if you've been working out for a long time and already have a good strength base that getting only Meso 3 is fine. I still think you can do one rep max's, or you can just dig in. I did each meso week twice. The first week I used what I thought were good starting weights based on my fitness level, recorded it and the next week I made sure I went up on weight for whatever I could even if it was for only 1 set. I then used that weight as the basis on how to progress to the next week. It becomes an 8 week program then
You could make it 12 weeks by then starting all over and going thru it again, doing each week once at all your heavier weights. Just an idea.
I have the whole set and thought Meso 1 was too pushup intensive for me and in general similar to her other higher rep workouts. She threw pull ups in Meso 1 which I can't do and in general are a tough exercise for even the most seasoned exerciser. So was a bit odd she had those in Meso 1, I had to modify and do something else. Meso 2 I did enjoy though, it was easier to split that one up into separate body parts than Meso 1 just on how it is structured.