The problem with on-the-job training is that the quality of it is highly dependent on the workplace and the coworkers around you and the job in question. Just

The problem with on-the-job training is that the quality of it is highly dependent on the workplace and the coworkers around you and the job in question. Just look at programming and software engineering. It takes very little to call yourself a programmer, and on-the-job training may or may not help at all.