I always get confused when someone posts an entry where the cut text is integral to the entry and the entry doesn’t make sense if you haven’t read the link (for example, if it starts a sentence which gets continued under the cut, or if pictures are captioned only in the cut).
Has to do with the way I read my friends page—I’ll typically open a bunch of entries in tabs, then read them one by one after I’ve finished “triaging” my friends page. By then, the cut texts are gone, since they don’t show up in individual-entry view.
Edit: Heh. Apparently I wasn’t the only one confused by the entry that prompted this one; on refreshing, I see that someone else commented, and the OP has subsequently edited the entry to add the cut text to the entry itself.