How often were crucifixion done?
Too often. Crucifixion was reserved for non-Romans (Roman execution was by beheading with a sword) as it was considered too barbaric for Roman citizens. Because the Roman Empire stretched over most of Europe and North Africa, there were many non-Romans to execute. A well-doocumented case was the crucifxion of thousands of slaves at one time along the Appian Way, a road that leads south out of Rome ( and is still there to this day). These were former sleves and gladiators led by Spartacus, who led the revolt of these slaves against Rome (just as in the Kubrick movie). So crucifixion was a daily event across the empire, and a very regular event in Jesus’ part of the world. No doubt the cross-beam that Jesus carried to Golgotha (the place of the execution) would have been used many times, and stained with the blood of countless victims who had been nailed to that beam before.