We all do things that we really probably shouldn't with our writing. Sometimes, this is forgivable. Follow the rules to a T and you will end up with some dull, dull dross. Ludicrously well written dross! But dross nonetheless. Other times, you end up with not-so-good situations.
For example, if I have a character who smokes, he smokes way too much. He will down enough cigarettes in a page to massacre a herd of bull elephants.
(As an interesting note, it's only ever cigarette smokers who smoke too much. If I give a character cigars, he'll still smoke pretty frequently, but about as often as someone with a smoking habit would ordinarily. If I give a character a pipe, it's basically just when they're at home, which is not often in fiction-land.)
This is largely because I do not know what to do with my characters. Most of it, however, stems from the fact that I am incredibly anal retentive in my writing. On the whole I'm fine with paragraphs, but there are certain shapes of paragraph that for some reason drive me so totally insane.
And so I pad.
PAD LIKE THE WIND!
I also pad because, as I noted moments ago, I really don't know what to do with my characters, and it feels weird just saying Character Q did action Y and leaving it at that for a little while. It feels like they need to be doing something all the time.
Apparently I have Character Deficit Hyperactivity Disorder.