Tom, I first noted this watching a video on Totonno's. I then tried it out and I was pleasantly suprise. To me at least, it's a whole different pie. Same ingredients but in a different order. When you place sauce on last, it typically is drizzled over the pie in patterns or splattered on the pie. Post bake, you get varying bites of sauce + cheese, more sauce less cheese, more cheese less sauce. It's just different and it's very good. Try it and see if you don't notice the same.
what I typically do for a cheese only pie, is to layer the cheese first, then splash the sauce down in various spots, then maybe sprinkle a bit more cheese on top here and there. You get a very marbled pattern to the sauce and cheese. Good stuff.