I watched a Julien Milchamp you tube video where he basically says if applying a scuff sheet then knocking in only takes about half the time.. I threw me at first but does make some sense he more I think about it.
Although I would say boneing the edges is not really possible with a scuff on so if it needs more in that area than has come from the factory then it might be worth removing and reapplying.
I would always recommend knocking in a bat
before applying a scuff sheet. On my personal bats, I only lightly knock them in and apply a scuff sheet to continually test the durability of bats from our bat maker (as inevitably we're going to get customers that don't knock in bats before using them) - however for all of the bats that I knock in for customers, I
always knock bats in fully before applying a scuff sheet. I've previously knocked bats in after applying a scuff sheet before - but these have been prone to cracks appearing. Whilst these may have been exceptions - since I've knocked in every bat before applying a scuff sheet, there have been no issues with premature cracks.