To me, it is a gimmick to compensate for blah stories and pacing. It's all psychological. "Oh, this chapter is is only a paragraph long! Awesome! This book goes by so FAST and is full of action! Never mind the action of this chapter involved the PoV brushing her hair. The next chapter is about the PoV putting her finger on her chin and saying, 'hmm.'"
If you are doing short chapters, I would rather there be a reason for it rather than making a 200 page novel turn into a 300 because of 120 chapter headings taking up more room than the actual text.
When I managed a bookstore, I asked my customers what they liked about Patterson novels. Most of them said, "oh his stuff is so fast paced, that it makes the book hard to put down." I would then say, "oh, lots of action? amazing story?" to which they would respond, "Not so much. I dont remember most of the story. But the books have short chapters!" That is a gimmick, and it bugs me.
Don't get me wrong, he makes a ton of money, and releases 4+ books a year, and tons of people read them. I just think if he put as much effort into writing a good story as he put into creating a false sense of pacing, that his books would be better. That said, this is not a thread for me to rant on Patterson - i mean, it's not like im a gazillionaire from any writing ive done.