They may be looking for postings from their actual friends that happened while they were offline. Boredom is't the only reason for scrolling. And if you're pushing actual friends down the page by spamming my feed, well, I'm going to think a little less of you.

> (Or if they're drilling down through the timeline, bored).

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.