Both methods are equally valid. Personally, I lean towards one and the other. It all depends a bit on the context of the trip in my raw fantasies; how I imagine myself being staged.
Flagellated and then loaded with a heavy patibulum, then making my way to the place of my crucifixion, barefoot, walking on rocky ground, under the jeers of the crowd. It must be painful enough to have this patibulum on my shoulders with the whip lacerated flesh, the pain must be terrible with every step. If I stumble during the journey, the guards' whips will fall mercilessly on my bloody back; will I have the strength to get up and continue my journey, it will all depend on the distance I have to cover.
Whatever the method, the nailing will be horribly painful. I would prefer to be spared the journey.
That is why I imagine myself being led to the place of my torment (in a crowded arena of excited people). There is a heavy cross on the ground (or several, if multiple executions).
Surrounded by guards I am taken directly from the dungeon into the arena; so my body is still more or less intact at this point. (unless I am tortured before my trial).
I will undergo my flogging tied up, drawn and quartered, between two posts. My cross is just a little bit behind. A hole has been prepared in the floor to hold it in position when raised.
Whipped with blood flowing from the back and front, I am quickly untied and pulled backwards, quickly tipped over, with my back on the wood of torment.
loincloth ripped off. Excruciating pain that twists my body and brain as I am nailed. Four nails; one for each arm, one for each heel. My body twists in all directions. The pain is so excruciating that my bladder fails me, a great stream of urine floods my bloody, torn chest. Mockery and slaps from the executioners. Further excruciating pain as the cross is raised and pulled upright with ropes. Terrible shock when the vertical stripe is lowered into the hollowed-out hole in the ground and the executioners hold it vertically with wooden wedges that are hammered in with sledgehammers, the shocks of which reverberate throughout my body.