Since this door was relatively flat, we decided to do ResoNix Squares over the plastic panels we added, then full coverage with ResoNix Rectangles. We know that full coverage is well past diminishing returns, but the price difference in the extra amount of ResoNix Rectangles wasn’t enough to justify the extra labor it would have taken to meticulously plan, cut, and apply them. 100% coverage on a relatively flat panel requires no extra thinking or planning and you can finish it up much quicker vs. planning. For your situation as a DIY’er, this may not be the best route, but here at the shop, time = money. The product cost less than the time we saved going this route. Plus, while it is past diminishing returns, more is better after all.