Awesome spit paints! Loved doing those a while back.
When I did speed paints just to show off speed, I didn't find myself improving at painting one bit. What really helped me tackle my mistakes were working on individual skill sets, e.g. Edges, Proportion, Values etc. during a session of studying.
Right now it seems your edges and drawing could use some honing. Maybe take some time to do a study of something simple, focusing only on painting good soft edges, hard edges, while making sure nothing overlaps incessantly. As for drawing, maybe doing lots of slow accurate/measured line drawings can help, especially from multiple angles to aid understanding of form.
Also, the best book I've found on improving any skill was this book Peak
Hope this helps, keep it up!