I'm finally caught up, so I hope y'all don't mind if I give a few thoughts.
I think the perp is pretty good at disposal of evidence, actually. I think the bookbag drop was the riskiest in a way, because it was closer to possible witnesses. I think that's important.
As far as dumping the body ***GRAPHIC***, I think he just didn't want it near him or his house, for obvious reasons. I don't think he went out of his way to hide it because he doesn't really think anyone will think of him for the crime. More on that in a second. I do think he might have dismembered the body because of his DNA on the body. I think he did not dump the parts that would show sexual assaults or her fighting him back
He was probably much more careful about where those body parts are (burned/buried somewhere farther off a road is my guess).
I don't know whether the main body dump was meant to shock, but he certainly didn't care if it did, at least.
I think he may have someone near him who would notice large packages (parents, close neighbors, etc). The parts he dealt with separately might not look suspicious in their bags or boxes. Or he meant to shock with the 1st body dump and hid the rest better because of evidence. One or the other, imho.
The bookbag drop was probably done where he thought he'd fit in walking with a bookbag, imho. Or fit in pulling over in that neighborhood. That one is key for me. If he got caught carrying it or leaving it, I think he had a cover story that he thought would work. I do think the main idea of that drop was to get the focus out that way, but it was still such a confident move. He could have thrown it out a window in a remote spot farther away. He wanted that found very quickly, and he didn't mind doing it himself when folks might have seen him. Very odd. Is he very familiar with the people there and their routines, etc? Or is he just that cocky? Maybe he knows he looks like a million other people in the area?
I wonder whether that area gets car break-ins or anything? Are there streetlights out? Is there any reason for someone to expect that they could leave a bag out and not be noticed at all? It's such a bold move if you aren't at all familiar with the neighborhood.