Comment by Desafinado

In any sustainable role you should get some natural lulls here and there where you can do a little extra during work hours. I don't intentionally block time out, but if a few hours present themselves I'll often take advantage of the extra time.

It's not entirely unrelated to your job if it's making you better in your current role. And if your employer doesn't contribute to your growth, you really need to take it into your own hands.