I'm pretty sure this is only visible on c/196 right now because it's grown to the point where there's a new post every 5-15 minutes.
Hours apart, I'll log on and see the same content on Activate/Hot ranking. I'm still seeing stuff from 24-48 hours ago in the first page, which is wildly different behavior than a comparable subreddit where you'd barely see the last 12 hours on the first few pages.
Can this be fine-tuned per instance or per community?
That'd have to be finetuned in the lemmy code and rolled out with a new version. Also, those algorithms are insanely complex, companies earn billions over those pieces of code.
Nevertheless, I'm certain someone's already working on it cause open source rocks