I don’t do much sanding with the scales on. Mostly because if they need much sanding, I fell they likely need a good going over at the pivot. I have done more with a good deep clean with steel wool and polish and left the scales on. It kind of needs to be assessed on a razor to razor basis. The proceed with caution and work more towards preservation certainly lends itself to leaving the scales on. If you feel you did not go far enough you can go back and take them off.