Slot machines, FarmVille, Twitter feeds, I think they all work the same: push a button, you might get a reward. I'll leave it to the armchair psychologists (or even real ones) to put a label on it, but that's the commonality I see in my own behavior. Or maybe it's just the constant influx of stimulation, I don't know.
What I do know is learning to sit and do nothing is valuable. When data-connected phones came out, I thought it a boon because never again would I need simply stand in line. I could check email, surf the web, fill that time with something of "value". Then I realized that, for me, checking a Twitter feed isn't of any more value than just standing there aware of what's going on around me.
I've noticed the same pattern as my access to technology has expanded. Initially, I was completely unconcerned with my online presence, but, as the years wore on, it became less of a relief to be away from everything and more of an impatience to get back and check Twitter, email, news, etc. Unfortunately, I'm not sure that there's a way to go back, either for myself or for society as a whole.
You say that you quit in the past and still find yourself in this situation. It's time to quit for good. Delete your account and never look back. Don't worry if your are missing out something, eventually this feeling to check everything will fade. I delieted my facebook and twitter account about 2 months ago. It was taking up too much of my time and I'm glad I did. I still use Google+ but I feel like it doesn't take as much time from me as the other networks, I don't even check it every day.
The ideal for me would be to maintain the accounts, but use them less. I'm worried that being completely without any social networking presence could hurt me down the road with companies being reluctant to hire someone who seems like they might have something to hide. In my opinion, at least, this attitude is ridiculous, but I've already had people look at me strangely about it.
I took breaks from Twitter a few times but always quickly got back to my previous unhealthy usage. The way I finally stopped was to delete my account. Simple. I eventually created a new one when I wanted to go back but abandoned that after realising I had zero followers and building back to the previous level would take too long.