I think categories are a huge waste of time.
Once upon a time, there were categories even in generic search engines (Altavista, Excite, Dmoz) and people were somehow used to it. Now that we all use Google, I doubt people even notice categories exist.
So whenever it's possible, I don't choose categories.
And if it's a "low earner", I don't submit altogether if categories are required.
Please, wannabe new stock agencies take note!