RIght on. Better worded than I wrote.ALWAYS follows the manufacturers instructions. Never guess or do what YOU think. If warranty is ever an issue it will come back to haunt you. Extra nailing is required among manufacturers for steep slope and high wind situations. Nailing with 6 nails in normal situation is not needed.
That answers alot of questions, what do you think happen here?Just west of the coast here. Depends on expoure to the weather. I use from 4 to 6 'depending'. Since most other rooferrs nail above 5 1/2", their shingles slide off before we have to worry about how many nails or weather.