It really does not matter if the footing comes back onto the shelf. I have all my arrows footed. Been doing it for years. Makes that carbon “bomb proof”.
There is so many ways to do it. Tinker and see what you like.
Heck, I have even took the Carbon express Bulldog nock collars and used them. They actually work pretty good as footings. I would not recommend them solely, but they work pretty good on your everyday arrows.
I personally like my footing 1.5”-2” long.
I also agree, if you make them yourself, taper the ends of your footings. Makes a cleaner pull on the target and if the footing does come in contact with the shelf material, it saves on it.
We sell many sizes on our site if your interested.
Basically, I cant recomend them enough! They really strengthen the carbon.