Learning On the Job
Consider how often we accord honors to achievements which do not represent, when one looks beneath the surface, any serious expertise but only an acquaintance with the subject or the responsibilities.
Despite all of the deference given to diplomas and certificates, life is largely a matter of on-the-job training. You study the subject formally and then learn the real nitty-gritty later on.
There is a reason why many professions are called "practices."
The medical profession, however, is ahead of the game in this respect. It requires a significant amount of real world experience via internship and residency.
Colleges should be filled with apprenticeship programs.