Wow, I can see a lot of improvement - in fact it looks like the sketches are from two different people.
I am a complete beginner so please, take the following with a pinch of salt, but I thought the thicker / darker lines worked much better on some poses than others. It took me a long time to try and work out why I felt that way and I think I may have an answer.
If I number the poses 1 to 7 (123 top row, then back from left second row 4567) I think in pose 6, the thicker lines convey a little of the shading, i.e. the parts that will be darker in a finished drawing. I feel like the person is crouching and as if looking downward, the light appear to come from behind and above, so all that is in the front is darker, and that is where you placed the thicker / darker lines.
In comparison, figure 3 for example, the dark lines are marking both the back and the front, it gets very confusing for the eye and although I think the proportions and position of limbs etc appears right, the body ends up looking twisted...
Anyways, as I said, I think your figures are great and I wish I could get to your initial level! Somehow, I cannot for the life of me get any proportions right! All my figures have got super long middles with short legs.... :-(
You gave me hope that I can maybe get there!
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