Just a comment: I haven't found a spec that works for me on all pickups & guitars; my method is the old fashioned seat-of-the-pants one, using my ear- starting very low, I'll raise it 'til it sounds good, raise it more 'til it doesn't, then lower it back to where it sounds best. I feel it helps to hear the whole range before settling on a final position.
One thing to remember if setting to a predetermined height- you measure it with the string fretted at the highest fret.
It's also worth mentioning that on guitars which don't have have individual volume controls for the pickups, height adjustment is a way of fine-tuning the balance in combined switch positions. Sometimes when pickups are set for the best tone on their own, the in between positions aren't ideal. A bit of tweaking can sometimes improve this noticeably.