How to get the most prisoners?

[AegonTheUnready]

I often go on raids and siege down holdings. Sometimes I get a half dozen prisoners, but most of the time I get none.

What determines where prisoners are hiding? I.E., if I siege two holdings, what choice should I make to increase the chance of coming away with captives?

 

[Sergeant Flutter]

Go after provinces where there are more courtiers. I think it's a simple die roll.

Sacking Rome usually gets you like, 15-20 prisoners.