Steve Barker writes:

This is wrong also! The number of quarter turns is dictated by the
weight of the door AND the caliber / length of the spring.

You're both wrong. Full turns equal the height of the door travel, divided
by the drum circumference, plus about a half a turn. Opening the door with
insufficient winding will lead to slack cables hopping off the drums, and
then disaster, so the extra half turn is important.