1. Instead of measuring, I just held the piece upside down for the length. 2. 12/12 pitch means it’s a 45° angle. 3. The relief cut in the on the waste side saves a little bit of time 4. Snipping off the corner makes installing it easier All these little things make a difference in efficiency. Think about the little things and it will add up to saved time or ease of installation. And before you comment on the Tyvek or the gable trim - the homeowner did it and is a DIYer and a friend. I just came