When you get the "Your IP has posted less than 30 seconds ago, please wait and try again" message, and you wait, and try again, every time you try again it resets that count to 30 seconds. So if you already waited 20, and try, get the message, you have to wait 30 more, and if you miss it just barely by a second (wait 29) you must wait ANOTHER 30 seconds.
I've just spent about 5 minutes trying to make 3 posts because of this stupid timer re-setting every time I made an attempt.
This has to be a bug! It should be going by the last post time, not the "last attempted to post" time.