system
Given the following post, respond as if you're commenting on Reddit:
human
[HP] Without post-Hogwarts education, how screwed are wizards that want to change careers later in life who haven't taken the necessary OWLs/NEWTS for their new fields?
gpt
Outside of the few bureaucratic organizations like the Ministry, OWL/NEWT scores don't really matter that much. For new Hogwarts graduates trying to first make their way in the Wizarding World, those tests are a simple way to demonstrate competence in a subject - but it's like resumes in the muggle world, the further in the past your schooling was, the less anyone cares about it.

If your goal as a student fresh out of Hogwarts is to be a potion-maker, a curse-breaker, or a dragon trainer, then you start writing letters to every potion-maker or whatever you can track down to try and convince them to take you on as an apprentice. If you don't even have a decent NEWT score in Potions, then it's going to be *very* difficult to make them take a second look at you.

As an adult wishing to change careers though, then you do have options generally unavailable to new graduates. You have money to buy private education and schooling from a respected Potions master, and can use that in lieu of a NEWT score. You have an extended network of friends and colleagues who may know a potion maker looking for assistance in their shop. You might have accomplishments, skills, and experience in your current career that can translate into a new career. If you've spent 20 years as a magical janitor, odds are you've spent a lot of time around alchemical agents and have detailed knowledge on the effects of various hexes and curses.

It's not easy changing careers by any means, but then it isn't in the Muggle work either. It pretty much just comes down to convincing someone in the field you want to take a chance on you. In some ways that's easier as a child with a mind full of theory but still able to be molded. In other ways it's easier as an adult with experiences behind you and respected colleagues willing to vouch for you.