I take great pride in my work. But I will almost always value the knowledge of someone who does this as a full time job above my own. There's no substitute for experience. Hours at the bench. I was merely pointing out that this article comes from a credible source, which should not be taken for granted on the internet. No intention to devalue anyone's work, beyond a little harmless self-deprecation.
I agree with the experience aspect; you should spend all day repairing if you want to become good at it, ideally by specializing. Practice quickly disappears, but it can be caught up.
The question, however, is whether that's all there is to it, or whether there's more to it than just repairing cameras.
I ask this from the perspective of an enthusiast who doesn't have to earn money from their passion.
For example, the entire theoretical background is ignored when repairing.
Why current flows through a transistor or what the field strength of an electromagnet is is irrelevant as long as they work. And if not, it's about troubleshooting and replacement, with the complex newer SLRs, usually following the instructions. I don't need to know anything about electronics for that, but I should be confident in soldering, etc.
Combining practice and theory—that would be my goal as a DIY enthusiast.
Why does this potentiometer work like this? How is the LCD controlled? Why does a lever have these dimensions?
You never get to the end of it, while the 15th repaired Canon T90 becomes routine, which isn't my score, sadly
A professional probably doesn't have time for such excursions; he has to take care of his business. Which doesn't preclude him from continuing his education, of course.