The point being: Having the inspection prevented me from having an S-trap that I likely would have had if I or a plumber had done it without inspection. In my case it was particularly tough because I had the floor joists, cross bracing 2 water pipes, and another 2x4 to negotiate, while the drain was moved over 2 inches from where the original was. It was doable, but was great to have a master plumber verify my final solution wasn't an S-trap.