You made yourself something that sounds like a really fun exercise :D Make an attempt at Tetsuo Hara drawings too, and post your work :D I see some of the lines that are very close to the master's drawing, like on the jaw and some of the shading, keep up!

Really nice, I'm really curious about how 13 and 16 would look like finished :D Especially 16, it has such a nice posture

Had to tilt him a bit, cuz I draw him too big for the page :))

Hi there! I think your supposed to look back and forth at the drawing and picture, you are trying to reproduce what your seeing in an image so you do need to look back at it a lot, so thats totally normal in this exercise. Also getting into the practice mindset is hard for me too sometimes, this might be the reason why you are tempted to get distracted, maybe you dont like how you drew a specific line and your mind's just like" fck it, im out", at least this is how it is for me sometimes, but each time is getting easier and easier to focus, especially if you start to allow yourself to make big confident lines, its much more fun than just drawing little lines and worry about every single one of them. Based on your drawing this might be something for you to work on, drawing big lines, you could challange yourself to draw the body of the snail from only 6 lines or something like that, or to do the inner side of the boot from only one line. Keep going & have fun! :D Regards :)