i don't think there is a limit. there is a well documented plan to make 4chan unusable by constant spamming of low quality threads. this has worked quite well. last week i made a count. 140 1pbt(y)id threads. most of /pol/ was unusable.  /lit/ has a posting bot doing the same thing, fonatantly recycling the same threads.  /hr/ is 95% celeb threads with the same disgusting coomer replies in all of them. it would make sense that any general type thread and any organic thread be disrupted by spamming to the bump limit. this kills the persistent / long form discussions as the earlier posts get archived. i've seen this happen multiple times. often there are two spammers that pretend to argue with each other, when their real intention is to cause the thread to archive by posting off topic garbage.  there is probably a better rate for creating new threads, as some thought goes into keeping them somewhat relevant to the jews of the day. but for thirdies a pay day is a pay day and spammimg is aan easy means of getting it. its better than picking bananas.
Australia