It's interesting how things propagate across the #FediVerse. It's a lot more complex than the old Usenet flood-fill system. Because it is driven by follow and relay relationships, of course, and nothing makes it everywhere.

Mastodon.Scot and Toot.Wales have automatically picked up very little of something that I did yesterday. MastodonApp.UK has picked up some of it. But little old almost unknown Mastodon.London has picked up almost all, except for the part done on a node in Florida.

This agrees with my educated guess.

Mastodon.London is the least likely, with the fewest relevant follow relationships, to have this stuff already locally cached. So it fetched almost all of it afresh on demand today. This implies that Scot and Wales, two well-connected nodes, had the greatest amounts of this stuff already locally cached.