This happened to me last year and I just remember again when I view my PM history. Someone report all my previous post. I received bunch of deleted post notification on my inbox for more than a week then I received temporary ban for 7 days afterwards
No matter how long it might have taken them to discover a post to be deleted, once they know this fact and have clear evidence it's not worth it, it will surely end being deleted, if you it seems ok by you doesn't means it's fine and ok by others, moderators keep to their duty roles by monitoring this.
Question: At what certain amount of deleted post will cause a permaban?
I don't think a deleted post can cause a permanent ban but the content of what you posted is very important as well, they may be suspicious activities you may not know.