Really. I know of no one that files a brand new chain or checks the rakers. Ole feller I've been selling and putting on new chains for over 20 years. In my 20 plus years I've never had one person ask me to touch it up with a file or check the rakers. They, like me, assume since its new its probably already sharp and the rakers are right. I've yet to find a new dull chain in a Stihl box or one with the rakers outta wack. Let me tell ya what I have heard over and over, "nothing cuts like a new one". I hear that all the time.
I know there are folks than can hand file a chain and it cuts great, better than new, I've yet to see it, possible I guess but to actually see it, never have. I've heard it said but never seen it. Sadly for every one person that can file good there are a 100 who can't. Few human hands can hold the angles like a machine can. I got many customers who hand file their chains a few times and then bring them back to get the angles striaghtened out with the grinder. That goes on all the time. The human hand just isn't that steady or accurate, the machine is.
I think this filing thing is more self satisfaction that its cutting again than how well its really cutting. It feels good to be sawing, chain goes dull, touch it up and its cutting pretty good again. Feels good yes. Cutting better than it was new, I doubt it. If it is awesome, I know my new chain is cutting like what, ya got it baby, a new one, cheers!!!!!!!!