i just wonder how many post maximum in a day that we can post, because i see my friend got banned after he did post much in a day.
It's not about the quantity but the quality of posts, so if you're making dozens of low quality posts a day just to rank up then this isn't going to be acceptable. Posting exclusively in crappy off topic threads isn't acceptable either and if you do so you'll be banned as per the sticky in there.
I.e. posts like this:
i'm Pop Rock, i never listen slow and acoustic type of music.