I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks