I think that he was not looking directly at the quality of the posts here, but only at the number of deleted posts by the moderator.
The users on my blacklist are tagged with the number of reports I have personally submitted against them (which were marked Good). Names on the list have at least 50.
Time between posts is not entirely important. I have certainly opened multiple threads and replied concurrently before submitting on more than one occasion.
If concerned about spam or post quality, the simplest method is to open up the thread. Redundant reply or non sequitur will encompass most cases.