There is no total number of posts for a week or day. There is just a wait time between posts, sort of like a cool down time to stimulate users to read more then they post. Here is how it is calculated based on your activity;
waittime = 360;
if(activity >= 15)
waittime = (int)(90 - activity);
if(activity >= 60)
waittime=(int)(34.7586 - (0.0793103 * activity));
if(activity >= 100)
waittime = max((int)(14-(activity/50)), 4);
The higher your activity, the shorter the time.