Tim Hardwick, writing for Mac Rumors:
Stationery Pad is a handy way to nix a step in your workflow if you regularly use document templates on your Mac. The long-standing Finder feature essentially tells a file’s parent application to open a copy of it by default, ensuring that the original file remains unedited.
Stationery Pad doesn’t get much attention these days, but it’s a neat alternative to repeatedly editing templates and using the “Save As…” command, which can lead to overwriting the original file if you’re not too careful.
I had no idea this existed. I will most certainly be making use of it in the future.