Enemy Size

[maltz]

For some enemies I see almost no growth in their numbers (pathetically little armies), while others grow pretty fast with me. No matter how late I challenge them I get a kick in the groin.

I wonder what decides the size of the encouter?

(1) Game Day? - Does the time matter? (Later in the Day = more creatures)
(2) My own level? - Does that mean I will have a easier time by NOT leveling up?
(3) My own army strength? - So should I always use high-quality-but-appear-weak units?

Thanks.