The roads outside Roman controlled cities were lined with stakes. Typically, the victim would carry the crossbeam from his place of incarceration to the stake where it was hauled up on the fixed stake. The bodies of the executed were commonly left hanging for days as a warning to other would be law breakers.
"Incidentally why do they still sing a Kindom Song "He died upon a tree to set all mankind free", I suppose it rhymes."
The Romans would also make use of trees that lined the road. They would be used as the stake and the victim, nailed or strapped to the crossbeam, attached to it.
Cults like the WTS have a need to be different. The upright stake doctrine is probably just another means to this end.
chappy