On a 24" bar. Compared with a box of files a dozen at 14 bucks (and it usually takes at least one file every time). 20 bucks for a burr isn't bad. I can run them farther I use 20 as an average. Depends on how you use them, how much material you remove at one time and if you happen to turn them backwards, then they are good for one tooth....
I don't care how good you think you are at hand filing, you can't compete with a jig mounted cutter for repetitive accuracy. Like I said previously, the Timberline is no good for 1/4" PICCO chain on a short bar ot maybe I should say it's doable but a PITA.
I'm happy with mine and obviously they sell a bunch or they wouldn't stay in business.