BestChange, for example, implements a rule that only 2-3 posts made on threads beyond 5 pages are to be counted. This is because mega threads are usually full of spam and posts beyond the 5th page are more easily missed than those made in the first 2 pages. Also, posts that are already buried deep in mega threads are normally less interesting because they are most probably just repetition of earlier posts, and posters probably didn't even read everything before joining the discussion.
Personally, I feel that this is a horrible rule and creates a ton of spam as well. I have over 6000 posts and I don't think more than 5% of them is written in threads that have less than 5 pages.
These threads are usually the 'most worthless' on my list when evaluating who writes where and what.
Forcing someone to open a 'how was your day in crypto today' spamthread because a post in Premier league thread is considered as spam is, well, not the best move you can make as a campaign manager.
Well, the campaign didn't actually require to post only on threads with 5 pages or less. After all, who can tell whether or not the thread would grow into a mega thread? What's preferred is that posts are made within those 5 pages. The discussion would continue and create 10, 20, 50, or even 100 pages more. As a matter of fact, you can still join in those kinds of discussions provided you don't focus your posts there. And for a campaign seeking visibility, that's understandable. Posts are quickly buried.
Certain threads in gambling discussion are rather unique. And it's completely understandable also if they grow into mega threads. It's because they're not discussing a specific game or event or tournament or a similar topic. They're basically covering leagues and sports. You mentioned Premier league. There's also the NBA, La Liga, MMA, ESports, and others. They're general topics. They don't have an end.