Then how would you know?
its as if a translator is needed with you. I thought we were both speaking english.
For nearly everything else, I use a shallow primary/secondary combo and polish the tip of a tool at a high enough angle to avoid damage. This takes about 30 seconds. It's documented, published, I've demonstrated it on video with a totally dull tool.
Faster than what sellers shows, what you describe and better results. Less to purchase, and far more consistent.
For mortise chisels other than very tall cross section chisels, I *always* do something that I don't usually do otherwise - hone the bevel of a chisel flat. I don't know that you have the nerve endings to understand why that would be done, and I'm guessing you're going to tell us to drill and pare or drill and mortise with the back side of the mortise chisel or something else of the like - negating the function of the tool and making the work less easy.
Go for it. A round bevel creates sloppy progress bevel down and mortising bevel up negates the ability to rotate chips loose at the bottom of the cut and causes you to cut directly across the grain instead of up the grain (the latter is far easier) without tilting the tool.
Oval bolstered mortisers and other deep mortise chisels are only sharpened differently because they are in a deep mortise and loss of bevel control isn't much of an issue deep, and because a giant bevel creates friction (such a problem doesn't exist with firmers and sash mortise chisels). I didn't read nicholson or parrot an instructor from the 1950s to figure these things out, I used the tools instead. Oval bolstered chisels don't have an overall curved bevel (it's flat between the top and bottom) for a very specific reason - the top is rounded over to adjust deep in mortises (if it's left sharp, at depth, you can't adjust the chisel up and down in the mortise without fully removing it from the cut), and the tip is rounded over or sharpened at a secondary high angle because the primary bevel isn't steep enough to hold up.
If those tools worked better rounded from top to bottom, the grinders at the factories would've shipped them that way. They either shipped them as I described, or perfectly flat as they're shown in the marples catalog. They're grinding them on a round wheel - there's no reason they'd make them flat on the primary for ease.
I haven't ever seen anyone talk about all of the above, but i vaguely recall you talking about cutting mortises with the bevel facing the open side. I couldn't tell you for sure that nicholson advises any of this, only that nicholson is a good way to find out when you have a scrub plane and can find no place where it's an advantage that it then becomes unsurprising that a text written with care for accuracy would confirm that. And then once you've laid the foundation, you may learn nuances from the text that you haven't discovered by doing.
If you're afraid of getting better at something, then nicholson is probably a bad thing to look through.