I've reached the point where I would have quit if I was doing this by myself. But I am not going to quit so long as I have these (not cheap) prepaid sessions scheduled, and I can keep tricking the "don't want to do no more" parts of my mind by signing up for more whenever it's not paying attention.
I was still pretty stiff in the legs, which didn't help, but I did pretty good this time, I think. We did deadlifts, barbell rows, dumbbell tricep curls, and closehands pulldowns. Several times, especially in the deadlifts, my limiting factor was the gripping muscles in my forearms, or the little control muscles around my back and shoulders, instead of the actual "target" of the exercise. But that's ok, that's why free weights are so much harder than machines, and all those little muscles need to get stronger too. Arguably, it's even more important that they get strong than the big muscles.
Next Friday is the last major group, and then we start the cycle over again.
When walking back up the stairs to my cube at work, I introspected the "pain" in my legs, and realized it really wasn't pain at all, at least, not like the skin sensation of "something is damaged". It's just "lots and lots of sensation" deep in my muscles.
I think maybe it's the proprioception nerve endings that are being overstimulated. By what? Donno. Maybe swelling or new metabolic activity in the muscle fibers. The more I read, the more I realize that we know so very little about something as basic as muscles and exercise. There is lots of "everybody knows" and "received wisdom" is that just piles of contradictory horseshit. We don't even really know what "stiffness" is! Part of the problem is that there are so few independent and pure researchers in this realm, and every theory that gets advanced gets instantly turned into a low value high profit pill, and/or a machine to be sold on late night TV.
In the meantime, I'll keep working out.