I don't mind if you want to challenge me on my words. It's far better than random insults about being closed minded, that's for sure
It wasn't the 15/30 perception that was based on experience, it was the pivot from right to left, or left to right. Watch the video, as I'm curious what you feel about the two example shots which are quite similar, and are certainly the same style or cut, just a little different yet requiring different pivot directions.
This is what I do to choose a pivot direction.
Once you have acquired your visuals, look at the shot.
For a cut to the left:
Does the shot need 'thinning' to make it? Use a left pivot.
Does the shot need 'thickening' to make it? Use a right pivot.
Be aware that a left 'A' pivot is the same as a right 'B' pivot.
If you are down on the shot, most people can see if the shot is not going in, either going to overcut or undercut. Just use the opposite pivot.
Once you have a lot of successful shots under your belt it really becomes second nature and you'll rarely think about it.