Why are you following 1,200 people? What is the point of your home feed? What are you trying to see?
Replying to people right after they post is how you actually get to have conversations with people, and get to know them well, imo
I think the part you're missing here is that there are certain parts of twitter where the density of interconnection is really high, so you'll know people because you see them in the comments of a lot of threads, or through retweets.
It's really not that hard to end up knowing 1,000+ people if you engage with a group or "corner" of twitter. Even moreso if it's multiple corners. (Like, AI, but also just frens, but also a little political corner, people from specific cities, etc.)
A scrollable feed of accounts that post interesting (to me) content.