A guy in Dayton told you one thing and now you're crediting the mud for 20 minutes of sanding time? That's a big claim for one change. Humidity, temp, how thin you mixed it, how long you let it set, the paper you're running, all of that moves sanding time way more than brand does. You also changed your whole routine when you switched, so how do you know it was the mud and not just you paying closer attention to your work? Plenty of guys switch brands and swear by it for a month, then the "magic" fades and turns out it was the same as before. Not saying the inspector was wrong, but one comment and one brand swap isn't proof of much.