I like the worked. I can see you put a lot of effort. The line works are mostly clean but still bumpy in a few places. The forms are very well placed. I would comment a few points:

1. Work with shadows. It will help read you drawings a lot better. It will also help separate front from the back.

2. I saw so many crosshatch that you did. Aesthetically it working but just as uncomfortable says you just a single contour will work better. I will needlessly take over the space. The 3d story has vanished from the drawings. Notice how the ones with less details are the ones looking much flatter.

3. You need to put more thoughts in you marks. It will help a lot.

4. Also these exercises are meant to be used a warmup. So, I am thinking you grinded a lot. Just take it slow. I am also doing a lot of drawing like you but taking it easy. I am taking these as warmups or form study.

5. I also noticed that you are replicating light. Leave it for now. Focus on the marks. Once you control the marks properly creating values is just mark making. It will not be hard once you understand the forms. I would say try to represent the thing with less marks. That way you can have control.

I am not an expert myself. I just draw for recreational purposes but these are things I understood about drawing. So good luck.

Finally great work!!!! Keep it up.