Now if you were to promote all those 10 posts, and 99% of your fans would see them all, then most will get annoyed. And if they don't get annoyed within the first day, they will get annoyed soon enough,
The most important metric for businesses using social media is engagement rather than raw reach, IMO.
Who isn't? :). Don't you always scroll the timeline down until you find a post you've read when checking Facebook last time? I certainly do.
It does depend upon the page, though. If your posts get high engagement, it will have higher distribution. Of the author's 55k fans, only 14k fans are "talking about" the page, so they'll have less than full distribution. To be frank, their posts are not getting many likes. Thus, my recommendation to just do one great post per day. Also, I would suggest to the author to experiment with photos and not just links with photos. Facebook's push toward bigger photos in the feed is no accident -- they work.
There are definitely brands that have multiple posts per day, and it's largely because of the high engagement their posts drive. Two examples that I follow are "I Fucking Love Science" and "Humans of New York." They both have fewer fans than talking about, and both post multiple times a day. Because their content is highly shared, it gets great distribution. It also depends on your own engagement with the page too, as I understand it.
The best practice I hear about Twitter is to indeed publish multiple times a day. Because it acts more as a true feed and not a digest, repeating the same content at a different hour is considered to be good.
I don't disbelieve your assertion that you personally would find it annoying, but I know a good number of large, successful blogging brands do indeed push to social media multiple times a day, and it seems to work for them. Several of said brands have indeed published articles suggesting that publishing multiple times a day serves to boost, not diminish, your popularity.
In addition, some counter-anecdata: I don't really use Facebook, but I've certainly not found myself put off by those blogs I follow which post that often to Twitter, for example. Indeed, I think I'd find it more annoying if they reduced their posting frequency - I'm not on Twitter 24/7, and if they only linked to their posts in a single digest-style tweet, I'd probably miss it.