At least leaving 5-10 minutes in-between his posts shows that he put a n some effort in constructing those posts, but in this case he posts less than 5 minutes on a multiple occasions, and that is unacceptable here in the forum.
There's no set standard for post timing like 5-10 minutes or lower. It probably comes down to the mods' judgment if they need to delete posts, even if they contain valuable content, or worse, give a temp ban to teach a lesson. If you look at it, there are also users who post with a long interval, sometimes hours, but their posts lack substance. So, we should weigh which is the bigger violation in that case.
I agree with you on that timing does not necessitate the quality of posts, but then having a member ditching out chunk of comments within 3-5 minutes Interval clearly state the obvious truth that there is no enough timing and efforts in creating such a comment regardless of the content and semetic load the comment Carries.
Although not everyone who takes time Interval to make posts out in efforts in fact someone may put an hour interval on his post and still make low quality posts, it all depends on the background knowledge of the member regarding to the topic of discussion, that makes up for the content of his comment.