I came to comment on this as well... there is an entire industrial workforce of CWIs(certified welding inspectors), who exist because welding a seam is not as easy as youtube would lead people to believe. It's easy to make it look correct, but it's the attributes of the weld you cannot see that make it safe/unsafe. Doing it correctly is not something you can learn from a book or listening to someone talk about...it's something you learn by doing it over, and over, and over, until it "feels" correct. The author may as well have included "performing a quadruple heart bypass" in their list of well-understood concepts.
A knowledge worker learns from repetition the "right way" to do things. Example rules like "document your work in a clear and concise manner" read a lot like "weld the seam from a consistent angle and with consistent fill material". Multiple people will follow those instructions, and you will end up with very different outcomes among the individuals doing the work. The sign of a well-seasoned craftsperson is that it "feels" right, and that only comes from long-term repetition.
Not a welder, but I'm aware of inspection procedures that use gauges to determine compliance with expected "shape" and consistency thereof. Also, x-ray imaging of welds and ultrasonic inspection of welds is a thing. You said "looks correct" and visual inspection is a thing but there are a lot of facets to that visual inspection that require some experience and tooling (e.g. magnifying glass, lighting, etc).
I came to comment on this as well... there is an entire industrial workforce of CWIs(certified welding inspectors), who exist because welding a seam is not as easy as youtube would lead people to believe. It's easy to make it look correct, but it's the attributes of the weld you cannot see that make it safe/unsafe. Doing it correctly is not something you can learn from a book or listening to someone talk about...it's something you learn by doing it over, and over, and over, until it "feels" correct. The author may as well have included "performing a quadruple heart bypass" in their list of well-understood concepts.
A knowledge worker learns from repetition the "right way" to do things. Example rules like "document your work in a clear and concise manner" read a lot like "weld the seam from a consistent angle and with consistent fill material". Multiple people will follow those instructions, and you will end up with very different outcomes among the individuals doing the work. The sign of a well-seasoned craftsperson is that it "feels" right, and that only comes from long-term repetition.