I just finished last week and I think you are going to love it!
I too was worried just looking at the high numbers on the workout cards each week. I thought, “I can’t lift that!” I had never lifted heavy before. I was surprised to find that I struggled less in Meso 3 than I did in Meso 2, that I just felt so much stronger suddenly. Also, the low numbers of reps always made it seem possible to complete the set.
I could feel the use of my core regularly during Meso 3. I felt my form was solid and I could focus on the muscle group I was working. I enjoyed chest and back the most.
I did squat rack legs without a rack. I used 20 lbs in a vest to add weight. I could have gone heavier with the legs but would not risk injury. I also “leisurely” used my elliptical machine on the long breaks during legs. I plan on doing plyo legs in the next round of STS.
Lastly, I continued to lose weight and see changes in my body. I may be in the minority but Meso 3 turned out to be my favorite of the three.