Your smaller studies look much better than your quick ones, don’t restrict yourself too much with those. Maybe use your three times a week to take three 1 hour passes at the same model or, as others have pointed out, treat it like a gesture sketch and keep the forms simple and elegant rather than hastily detailing in the smaller muscles. I think rushing through these is going to give you some bad habits if you don’t first practice doing it slowly (not that you haven’t).
Regardless, that you’re challenging yourself and setting goals is seriously the best thing to do. My little spurts of hard effort account for most of my improvement so I’m definitely jealous that you’re motivated.
The head is definitely distracting as a viewer. I always find it easier to sculpt the eyes closed until I have time and resolution to put them in. Maybe our brains are less critical of closed eyes because they have less varied emotions.
Maybe try starting from the mannequins if you want to practice getting the volumes, then switch back to zspheres when you want to practice proportions.
I really like where your wolverine is going by the way. The face is very well done and the base mesh is very clean.
