If it is forbidden to write two posts with an interval of three minutes, then it probably need to write about this in the rules? I did not know about this restriction. Thank you for telling me about this secret rule.
Actually there's no such rule about that, the forum system automatically prevents you from submitting posts in a small period of time, which decreases as your Activity goes up.
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);