I'm not putting down freehand sharpening. It certainly is less equipment-intensive than any kind of fixtured sharpening.
The reason I said it is less efficient is that as a human, there is human error with regards to maintaining the angle, so in order to get it sharp, it takes more grinding. ...unless you're saying that you're more efficient than a machine, on which the angle is mechanically maintained?
What HeavyHanded, DeadboxHero, and Eli Chaps said. They all know a lot more about sharpening than I do.

I agree that no human can repeatedly hold exactly the same sharpening angle, but that's not an issue for me. The worst that can happen (without getting sloppy about sharpening, of course) is that the edge gets slightly convexed, which is a good thing, IMO.