9:07 PM, Sunday April 5th 2020
One important thing to keep in mind is that when establishing whether or not you understand the primary concepts behind constructional drawing, going out of your way to pick unique or challenging subject matter is more likely to get in the way, rather than help you progress faster. Once your grasp of the concepts is more solid, then you can certainly venture into less standardized subjects, but until then it's just going to provide you with a lot of distraction.
There are a few issues I want to point out as being things you shouldn't be doing that come up in these drawings you've done, but I think it would be best if you tried your hand at another 3.
Here are some notes directly on your drawings. In addition to these points, I think overall your linework appears really stiff and hesitant. You're not drawing with confidence, you appear to be much slower, and it's clear that you're drawing more lightly when approaching the earlier phases of construction, then drawing with a darker line later on. If you look at any of my demonstrations, you'll see that I draw with the same amount of confidence throughout, and I don't purposely attempt to hide my underlying construction.
Also, for the snake, I'd probably do something more like the boxes on a string explained here, rather than sausages due to how sausages end up having joints that you would not see on a snake's body. The additional benefit of boxes is that it allows you to focus on how the snake's body has top/side/bottom planes.
Overall, these drawings aren't great. You've gone out of your way to focus on more challenging subject matter before fully establishing your grasp of the concepts with more simple, standardized subject matter. You focused a lot on detail and approached construction quite stiffly, rather than applying what was demonstrated in the various demonstrations.
Next Steps:
Do another 3 drawings, but with no detail or texture whatsoever. Focus entirely on construction, and choose more standard subjects, the sorts of things that are covered in the various demonstrations (including those on the informal demos page).