Well, that's what makes it so tantalizing! What did they leave out? What might we be missing in planing and all the rest?
I think this is probably like a golf swing.
Imagine what you could do to describe a golf swing in three pages if dealing with someone who had not been instructed at all.
Where does that leave someone who makes a living playing golf. As much as a lot of people who play for a living like to say they don't have that many rules, you'll find out how many of their bits and bytes you violate as soon as you play with them and suddenly they have volumes to talk about. Not going over the line at the top, not getting quick and keeping the clubface facing target at impact - all good stuff. Pretty basic. Course management, playing well when your heart rate is up (or even convincing yourself that you prefer that) is the separator.
I would guess when you get down to planing in the early 1800s, the basics look like nicholson stated them to be. If there's a more efficient way to do it, I'd like someone to share (but I"m open to learning about the more efficient way, aside from plugging tools into the wall). All of the little things that you do beyond what's written would probably take 10 times as many pages. You can match plane a joint with a few fairly coarse shavings and get this result:
For two reasonably well prepared boards, it takes less than a minute. It relies on some of the fundamentals that Nicholson talks about, but there is more needed.
Or you can do it any number of ways with checking and squares and all kinds of stuff and not have a joint that fits like this. This joint fits as shown (this is after glue) without applying any pressure.
That, in a shop where bookmatching anything, would be valuable. I would bet that it was universal. Why? Because I figured out how to do it without someone telling me anything other than that you can line two boards up together and match plane them. That leads to wondering how you can line two boards up and do it really quickly with nothing other than fairly coarse through shavings.
I don't play role play like some folks on here do, so I don't know what would've been a location (shop only) vs. regional vs. all those in the trade type secret. There is a lot of nuance in the plane setup and cap setting, etc, that goes into this, but it is effortless quickly - it becomes trivial - the key is in knowing what needs to be done. I haven't ever seen anyone teach what I did in this case - and is it that important? No - does it make hand work more pleasant than it would be planing, then checking, then taking a little off here and there? Of course it does.