Whenever one of your units gains JP from an action, all allies in the battle will get 1/4 of that JP for that Job the one is in.
That, I didn't know. I was wondering how the system worked that I'd be getting JP for a job I wasn't in.

But then how do I get JP for jobs that I don't have a person in yet? For example, I got like 150 JPs in Lancer, but at the time I didn't have a Lancer.

Anyway, thanks for the advice, y'all.

By the way, I think I'm just starting Chapter 2.