Everything should be on their website, plus posted to the top social media (by popularity) to make it easier for people who want a push feed.

They should also post to at least one social media site that allows full reading for free without an account and supports notifications (possibly only with an account along as that is free), unless one of the top sites they post to satisfies this.

The reason for this last is so that if there is demand on some less popular medium for these posts, someone interested could build something to subscribe to the feed on the free site and repost it unofficially to the other service.