There comes a certain point, where you can't really teach an old dog new tricks. It's like teaching a cow to sing.. It sounds like crap and annoys the cow.
There comes a certain point, where all that matters is quick, acceptable, easily repeatable results.
For the OP's friend.. all he needs is a Stihl 2 in 1. It'll sharpen the chain and set the rakers ( depth gauges ) in one shot. Or rather, in three or four strokes after every tank. Could you or I do better.. free hand, whatever hand, whatever method you'd care to name? Sure.. But wait.. There's that thing called a learning curve. Takes all the fun out of it for a newby.
Remember the first chain you tried to sharpen? Tell me, really.. how'd that go? Oh yeah.. that "learning curve " thing..
Realistically, the Stihl 2 in 1 should be called a "sharp keeper", NOT a "Sharpener". But, it will let a rank amateur sharpen a chain in the shortest time possible.
Also, it will teach you what 30 degrees feels like.. Every time you're off a bit, you get the bump when the butt of the tool hits the blade.
The design of them virtually stops you from screwing up. Just count your strokes, and mark the first cutter.
I've let people touch my saws who have no idea that I basically no longer hand sharpen. The common comment is " Boy.. is that ever sharp!".
Replacement files can be bought on Amazon, but they were actually cheaper at the Stihl Dealership. 3 files for $10.00 CDN.. Decent quality too!
I still keep my hand filing stuff ready, and my bench grinder for hitting stuff you can't see inside a tree, But, for everyday sharpening, gimmee a 2 in 1 anytime.