To pick an example out of thin air, think of stage act trying to keep a number of plates spinning. You can keep a number of them going, but the LRU one is the one most likely of falling because it's lost some energy, and you need to check it to keep it up in the air.
That's a great explanation for something the article didn't explain very well.
Still, LRU only works if they are of equal importance. Otherwise, work on the important one, even if you've worked on it more recently than the others.
A related idea is the "tyranny of the urgent". You can't let the urgent things keep you from doing the important things. (I stole this from a booklet with the quoted title, which stole the idea from the manager of a cotton mill.)
