What are they depending on?

I have 1 golden one and 3 silver ones with ~541 posts.

Nakiamiie has 3 golden and also 3 silver ones with ~590 posts.

Chrees has 2 golden and 2 silver ones with ~541 posts,
so it's the same amounts of posts (or close) to what I have, but a very different amount of medals..?

I thought they were depending on the number of posts, but that doesn't seem to be the case..
So anyone can tell me what they actually are about?
And no childish answers please, like "they only count intelligent answers, unlike yours".