Do you think she drove over to his place and they walked to the Lexus to go out to dinner, etc.?
I don't buy that NK was only at the house twice. If they were having sex three to four times a day and they each had to work eight hours a day, they were doing it at night. He was face-timing with Shanann and the girls most evenings from what I've read and Shanann would have noticed if he wasn't doing this from their home.
Shanann was apparently upset during some of the facetime sessions as he was watching television, was preoccupied and not paying any attention to the girls. I think NK was over at the house more than what she admitted to. It would have been quite convenient and it would have shaved a lot of time off her morning commute, also.