But then how did other people, mentors included, come to learn their jobs? Not everyone is theorycrafting in the game, so I'm sure the proper info is out there. And if someone directs you to a guide, then you check it out instead of relying on people to "teach" you your job. Also, on YouTube, I'm pretty sure there are videos about the different classes, and they usually mention the patch said guide applies to (same for written guides). The guides are usually properly updated too.
You'd be surprised, then, at how these simple trials go in DF.