Tearing off steep pitches

When tearing off a steep pitch, say greater anything more than a 8-9, do you prefer to set up the roof jacks to tear off, or do you prefer cleats and saftey lines.

I saw guys working yesterday on a roof and thay were basically relying on their harness and sort of repelling down the roof as they tore off. They banged it out quick, but is that really a safe way to go about it??