What's a reasonable number of posts per day?

I think the problem is they’re treating random threads like a place to come and hang out with friends. They go off topic and just spam random crap. I made a thread about changing the label “none” on some policy sliders to “minimum”, @Chantern15 and @Silviu200530 spammed the thread with posts like these:

https://forums.positech.co.uk/t/change-slider-for-capital-controls/17469/33?u=downunder
This has nothing to do with the topic at hand.

I have notifications set up. I understand that that could mean I’ll get a bunch of emails if a thread gets a lot of responses, I’m fine with that and can switch it off if it happens. It is, however, highly annoying to get ~40 alerts from a single thread in the span of an hour or two when the posts are irrelevant and the product of just two individuals.

This does not help at all, it clogs the forum and potentially hides posts that could actually be relevant/helpful.