I think a criminal feels furtively safe when he rids himself of items belonging to the victim. He feels discarding the cellphone and the purse & clothes disassociates him from the crime as it will become known in time. The pattern of the discards, however, does reveal his thinking during commission. He heaved the cell from the vehicle onto a field at the north east corner of Scheller & Santa Teresa. What is most likely? That he was heading either west or north. But then he disposes of the Juicy items again north and east of Fisher-Laguna and Santa Teresa, so the question is answered. He was heading north all along.
If the cufflinks bear telltale evidence connecting them to him and to Sierra, there could have been a temporary detour west on Palm when she made a protest that her bus stop was at Palm & Dougherty and Schheller was a wrong turn. But the eventual direction was still north.
Once the driver deposits the last items, he can cross Santa Teresa Boulevard on Laguna and continue all the way to Calero or he can stay with his pattern and come off Laguna turning right and moving north on Sta. Teresa. Since there are numerous places to hide a purse & books on the way to Calero, he needn't have stopped at the rusted shed. My money is on the driver continuing north on the boulevard.
The criminal's next decision is at Bailey and that has been discussed. Does he make a left turn at a controlled intersection on Sta. Teresa and pass the large IBM plant or does he, one more time, make a less conspicuous right on Bailey? I think he went east where he would find not only Coyote Creek Golf Course but Kirby Canyon (landfill), creeks and open land.
