I apologize for quoting myself, but I have given this more thought. Here is what I think is the most plausible scenario:
JRH pulled out of CFA
Around 60 seconds later he is stopped by the light at the intersection (it's a somewhat long light so he could be waiting 2-3 minutes)
He pulls out his phone and texts
Light turns green and JRH proceeds to office
He may have texted while in the car but not while driving.
Before this case started, I suspected that Ross was so distracted by his phone/electronic habits that he neglected to remember Cooper. While I have moments where I believe that there was actual intent to leave Cooper in the car, I am still not convinced of that, especially not when using the legal standard. I have always maintained that it is practically impossible to drive through that intersection without seeing THD Corporate HQ complex and that stopping at that light would make it impossible. However, if Ross was preoccupied by his phone, he would have been looking down and would have been completely unaware of his surroundings. IMO texting at the light would make prevent him from seeing the HQ, thereby triggering his memory that Cooper was behind him. It also explains the 5-6 minute trip time from CFA to the TH. Without catching that light, it would be hard for that trip to last more than 3 minutes.
Easily less than 60 seconds, especially is you are talking about where the turn lane begins. It could very reasonably be 30 seconds to be in the turn lane. Add 15-30 seconds to reach the actual intersection.
And that's accurate. It blows my mind how quickly Ross would have forgot.
