@felix the planet file is only released by planet.openstreetmap.org is only created once a week. So that file would be good for a week. There is a BitTorrent extension which tells clients to check for a new torrent file, so you can "update" the torrent with new data that would then be mirrored
@Coffee I think there has been some work on making #BitTorrent better for changing files like this. There's some extensions (BEP38 & 39) to tell clients to download a new hash, and for them to look at existing files when that hash changes. I think the internet archive pushed for these cause they use it.
But I have no idea about support for those features.