I couldn't agree more with WCollins!
Gustiness, crosswind ect should all be taken into account. If you really wanted to be precise then the approach should be worked on a factor of wing attitude to relative airflow ect ect ... but hey! at the end of the day too much science can kill the beauty.
1.3X is close enough, perfection is not science, it's an art! every aircraft, pilot and situation is different. Obi Wan was right "feel the force"
