I, too, used to wonder about this very often. I searched for a very long time, where I could find or buy avery 5160 label template. I searched a lot of forums. But it turned out to be much easier and simpler. There is a special template https://foxylabels.com/avery_template/5160
You can use it to create the perfect forms. In Google Spreadsheets it is much easier with the Foxy Labels add-in. But if you like Excel, you can use it too.