The S&W pistol armorer's manual for the 3rd gen guns, like most armorer manuals, is really meant to be used by someone who has gone through the class. It provides an outline to be fleshed out with lots of notes and hands-on experience gained in the class, not to mention with the instructions & explanations provided by instructors.
It contains simple instructions, following the proper steps, along with black & white pictures ... but it's knowing how to
perform those actions stated in the instructions and steps that's important. Being told to "remove this & that", with a picture of the parts shown outside the gun, after removal, may miss some important
"how to do it without breaking or damaging something" information.
The manual has plenty of room for notes to be taken by the armorers, as not everyone learns things the same way or grasps concepts quite the same. Notes are very important. My first armorer manual has LOTS of notes (which I still refer to from time to time).
When I was speaking with the fellow who's been writing the new manuals and rewriting/updating the old manuals, he said the 3rd gen manual was on his list to revise, but he's been too busy with new manuals and his other training responsibilities. There's a mistake (reversed orientation of a part in a picture) that's still in the 3rd gen manual, and which he said is on his list to correct at some point.
Also, the newer 3rd gen pistol armorer manuals don't contain a few of the corrections/repairs contained in my first manual, since there have been parts & manufacturing changes since then.
The older guns (with the older parts) are still out there, of course, but the general feeling seems to be that the older guns are probably not in as much use as the newer models, and armorers probably won't be seeing them quite as much. Guns are cycled out-of-service and replaced with newer models, after all. (Yes, I know,
personally-owned guns favored by cops often remain with them for a lot more years, like 1st & 2nd gen TDA's.

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Armorer manuals have lists of
Malfunctions, Probable Causes & Corrective Actions, and inspection lists ... but it's the extra notes, explanations from different instructors (and other experienced armorers in different classes) and subtle variations & helpful tricks that are added during classes that are really helpful.
Then, there's the new manufacturing changes and design revisions that have occurred since the last manual revision, and which have to be added by hand, by the armorer students, until the manuals can eventually be revised.
Mistakes are easy to make in classes, and that's with an open manual in front of the student, notes taken, an instructor demonstrating & discussing a procedure, and maybe even an experienced armorer sitting on either side at your table.
This is why armorers are generally asked to recertify somewhere between 3-4 years on most firearms, so they can remain current and up-to-date on all the manufacturing & design changes ... which might have an effect on how maintenance, corrections and repairs are needed and performed.
BTW, while the newer manuals being produced by various gun companies have much better pictures (some black & white and some color), as well as some computer generated illustrations, I still like some of the older line drawings in older manuals. Sometimes the bare, uncluttered line drawings made it easy to grasp some aspect of how something functioned, or needed to be repaired, filed, etc. (Of course, there was still the potential for making mistakes, thinking you were following the illustration the right way.

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FWIW, I've looked at a number of online videos posted by folks, and sometimes I wonder where someone got the idea to do what they're doing. Besides, even being able to completely disassemble a frame or slide doesn't explain how to inspect, gauge, identify and correct some suspected problem. Improper (or awkward) disassembly & reassembly can also present ample opportunity for damaging or breaking parts & assemblies, too.
Then, there are the tools needed for some of the gauge checks & repairs, and how to use them properly.