When should we consume culture in small, sequential bits?

I almost always read novels in bits.  That is, I put the book down for a few times before finishing it.

I rarely watch movies in bits.  That just seems wrong.  But, assuming we are watching on DVD, why?  Why do pauses ruin a movie but not a book?  I can think of a few hypotheses:

1. Movies manipulate our neurophysiology over a two-hour time horizon.  If we restart in the middle after a two-day pause, we are not worked up in the right manner.

2. Most books are longer than most movies, but there is otherwise no good reason for the difference in our consumption pattern.

3. We like the idea that we are "reading Camus," and thus we wish to stretch it out.  Few people get comparable status or feel-good values from watching movies and thus there is no need to prolong that experience.

4. We don’t actually like reading enough to keep on paying attention for so many hours in a row.

The ever-wise Natasha notes that we are mostly likely to read action novels — such as The da Vinci Code
— straight through without pause.  But action movies are the easiest to
watch in bits.  Ever try just a half hour of Jackie Chan?  Wonderful.  But breaking up a good drama is criminal.

Your thoughts?