Pretty much everyone has covered what needs to be known and done with feather burning.
Take the time to accurately tailor the the nichrome burner wire to perfectly fit the shaft diameter and length of fletch in question - which means adjusting the burner wire for distance from the shaft as well as centering the wire ends on the uncut section of feather you just stuck on the shaft.
To me, this is THE most important step. Keep working at it 'til it's perfect. If you change shaft diameters, you MUST start all over again.
With carbon shafts, don't let the hot wire touch the shaft!!!
If the fore and end of the feather doesn't burn clean ('cause you wanna make SURE not to have the burner wire touch the shaft) clean that up with a sharp scissors tip.
Make sure to add a drop of glue at either feather end when done.
Rake over the burnt feather outline a few times from front to back with a knife blade edge to dislodge the burnt feather dust.
While waiting for the 4" Vario Hunter Clipper to show up I'm gonna attempt the burn a similar shape that's 4" x 1/2". Setting up a nichrome wire to burn a short 'n' low shape ain't easy!
Really cool things about feather burning - the fletches are uniform in both shape and location, and you can concoct some very unique feather shapes. The down side is it usually takes awhile to set it all up perfectly (but ya only do that once, typically) and that horrific stink - yeah, the wife hates it, but it's the aroma of the woods and hunting to me. :D
Here's my 4" high feather burnt shape in a 4x4 fletch on an AD shaft - more surface area there than a 3x5 fletched arra ...