Fediverse

The experience will differ strongly between instances.

On instances with relatively few active users, there's often hours between posts to the local timeline. You'll be able to read all of those without problem.
You can even pretty much hold conversations via the local timeline without tagging people directly, and you probably know all active users on your instance.

On instances that federate with fewer other instances, the federated timeline can also be a lot less fast-moving and may lean more into certain topics, depending on what instances you're federated with.
I additionally filter out a ton of people and words, but yeah, I can often keep up with posts on the federated timeline on my main instance.

And last but not least, you can specify what languages you understand in the settings. Then it will filter out posts in other languages relatively reliably.