On the site formerly (and still) known as Twitter, I missed a lot because it did not show me everything from accounts I followed.
On Mastodon, I miss a lot because I wasn't browsing my feed at the right time.
This would matter less on Mastodon if my feed was endless and I could browse it until I'd caught up with everything new. But it is not endless, so I can't.
I don't see how you can have multiple instances all injecting stuff into my feed, which is what the (other) OP seems to be suggesting? I don't want any kind of algorithm deciding what I see and definitely not some kind of hyper-competitive inter-instance competition for my attention. But I wouldn't mind if Mastodon worked out what I hadn't yet seen from the accounts I follow and put it into my feed while I'm actually browsing it.