Posts will be limited to one very 5 minutes (per account), and comments will be limited to one very 20 seconds.

According to the code, it's actually 10 seconds.

And a side note: an author need to wait for 5 minutes to be able to post a top-level post after posted a new post OR commented on a post, but did NOT need to wait after edited a post, also no need to wait to be able to edit a post.