I just gave an personal example to flesh out my post. But if, for example, you are a structural engineer who has to consult on site with clients, you certainly

I just gave an personal example to flesh out my post. But if, for example, you are a structural engineer who has to consult on site with clients, you certainly need to recall a litany of data/concepts (random or non-random) pretty quickly if you don't want to look like an idiot. You cannot learn this knowledge from a few weeks on the job because the client would be able to see through your bullshit in minutes. This applies to pretty much any position that needs to communicate in real time about a base of knowledge (doctors, lawyers, logistics, any type of management position). If you believe that any career can be substituted by "a few weeks on the job", you're not really aiming that high for yourself.