I've read a few replies that seem to indicate that sharpening with <insert method> will remove more metal from the chisel or iron. The idea being that over time the iron would become consumer faster with one versus another.
For example, working the entire bevel each time for a convex bevel edge or a flat single edge would remove more metal versus a primary/secondary sharpening.
Assuming that the angles are kept constant I cannot fathom how a dual bevel sharpening removes any less metal over over time. For convex bevel and single edges, the same amount of metal is removed each time. So the iron's life (length) would be shortened by a fixed amount each time. The dual bevel method would need to remove exactly the same amount of material off the length but the primary bevel would only move every few sharpenings when it's re-ground to reduce the width of the micro bevel.
If any method prematurely shortens the life of an iron, it would be the tri-bevel method. The reason being that with every re-sharpening the tertiary bevel is removed entirely and then re-formed. Even so, over many years the difference is probably trivial. In fact, so little metal is removed with each sharpening that they are all trivial. It takes many, many years of constant work to use up a chisel or a plane iron.
Now wear and tear on sharpening stones is another matter, entirely. The fine stones are going to wear much faster with a convex of single bevel.
Am I wrong?