Sometimes, when I'm on Facebook, I'll get a notification. I'll click on it, and then someone has sent me a message. I'll respond to the message, and then I've got a new notification. This cycle repeats itself. (Usually it's not this direct; maybe I go and respond to an email, then a text message shows up, and then I get a new notification.) The point here is that there's some chain of reinforcement which catches me in a loop, repeating the same activities over and over.
Inside, though, it just feels like "Ooh, there's this cool thing I can check out! Oh wow, now there's this other new cool thing I can check out!"
This is probably just bad.
It's not the same thing, but I'm thinking about switching between tasks and the novelty they provide (more productive tasks, that is). Presumably there's some optimal pattern of choosing activities such that you can also reduce any feeling of fatigue.
But also, activities where you command your attention also tend to be more demanding. You might finish them and feel more tired. I don't know. Doing even normal attention-sucking things like watching TV or playing games also saturates really easily for me.
Maybe my general tolerance for doing the same thing is just lower than average.