Im in total agreeance with your first sentence. I think this was long thought out, extremely premeditated but yet what Terr did not plan nor expect was the one thing that IMO has derailed Terri's ENTIRE plan and that is she never in a million years thought all this suspiscion would fall on her. IMO she thought she'd come up with a brilliant and near perfect plan that by taking Kyron shcool, showing off what a good, proud stepmom that she was taking pix of Kyron with the science project that they had worked on together and then staging herself leaving making it to look as she had of course left him at school, she was in the clear, or so she thought. I think her biggest fear was would the teacher fall for the bait of the dr appt(as its not clear exactly how she told the teacher about the appt, did she really just come nout and say the appt was friday the 4th or just sorrta leave it open ended,hoping the teacher would assume, as she did , that the appt was for the 4th)once she saw she had gotten away with that along with the one other obstacle getting Kyron out of the school without it being seen that he was either with her or meeting her outside. Once she felt she had more than likely accomplished those two(and she'd have a pretty good idea by that afternoon whether she'd succeeded in both of those) so, once satisfied that she'd accomplished those two things along with all other details that her plan entailed (IMO the death of and hiding of Kyron) I think she felt she was pretty much 100% home free. Never ever IMO did she ever plan for the fact that she may have the suspiscion pointed in her direction. I believe she was fully ready to blame, blame, blame the school district and teachers for what happened to Kyron that it was negligence on their part that they did not protect Kyron from a big bad pedophile that walked into the scool and got Kyron or somehow lured Kyron out of the school and the school would be the ones at fault. Terri was trying her damndest to play the upset, grieving SM(IMO as was in that first PC I think she was looking to DY to get her que of how to act like the grieving mom, IMO you can see even then her trying to mimic DYs grief, but it came off as forced and unnatural and IMO the reason why is because she quite possibly is a sociopath and is not capable of feeling such emotions, therefor when tried it came off completely unnatural