Once you get rid of your newbie status it drops to like 60 seconds, or something really short like that.
Or you could just change your IP after every post..
You could always use tor. It will change your ip in less that 10 sconds.
But there are problems with tor since lots of the those ips are banned in this forum because of people abusing it.
Mine is less than 30 seconds now. It decreases with more activity.
And TOR is probably worse and more annoying since you have to re-log in every-time you get a banned connection.