Infield topdressing should be approx .25-.5 inch in depth. I was on a site this past week that had an infield with over 1.5 inches of topdressing. Here were a couple of photos of the infield.
As you can see, the infield was extremely loose, provided poor ball roll and poor footing. Bottom line - make the investment of a quality engineered infield mix and maintain a proper depth of conditioner.
Go to j-dturf.com to learn more about J&D Turf.