There’s a moment in every 3-4 day build when the fab part is put on hold and the decoration party begins. Filing lugs is part of the maker’s job. It probably goes back to an era when I was still a schoolboy and the parts were God awful crude pieces of shit that existed as little fixtures that held the tubes in place so a bicycle could be made. They were ugly or utilitarian at best and it got into he public psyche that adding flourishes or at the very least removing some of the manufacturing marks was a way to add value. I spend an hour on each joint for the very same reasons and do it automatically. Intuitively. By feel. While listening to pre-1970s Dylan on YouTube. I have this feed that begins with With God On Our Side performed at Town Hall in 1963 and it just goes on from there. Precious. At least 50 cuts and I never tire of them.
Back to said moment. All of it revolves around elegance. You want the lug(s) thinned a bit. Eliminate high and low spots. Make sure the flow is complete from top to bottom from side to side from front to back and that the same intention spreads to each lug so the job is the sum rather than the parts. At day’s end, this is about taking off some 3/10s of a millimeter wall thickness and doing it with class. You wanna turn heads, your own especially.