Where OCD Meets ADD

As a reasonably self-aware adult, I've noticed a unique pattern to my behavior.  It's not really troublesome or worrying.  It's just something that I know I do.  I become somewhat obsessive about something for a limited period of time or as I like to think of it "OCD limited by ADD".

I'm not quite as bad off as Melvin Udall. But, hey! 
Carol the waitress found all that weird behavior endearing. Right?

Let me explain.  I don't run around turning the lights on and off three times.  I don't stockpile bars of soap with which to wash my hands only once before discarding.  I don't have irrational fears of stepping on cracks or being waited on by strangers.  I just get really intense about a topic for as long as it holds my attention, and I've been doing it for a while.

Case in point,  I tend to get fixated on some sci-fi shows.  When I was 15 and hopelessly nerdy, gangly, and awkward, I became obsessed with Star Trek: The Next Generation.  I had my whole bedroom decorated with posters of the cast and schematics of the ship's layout. Yes, I could help you find 10 Forward and the warp core.  This was also during the summer where I decided that I must be adopted because my parents were clearly aliens and I locked myself in my bedroom for hours at a time avoiding their mind probes, err... questions showing normal parental concern.  But, my STTNG mania was just a summer thing.  By the following winter, the posters were taken down. They are still collecting dust in the closet of my childhood bedroom as far as I know.

Boldly going where no one has gone before

David Tennant: The 10th Doctor

More recently, I've become a huge fan of Dr. Who on BBC America.  I bought seasons 1-5 on DVD and even got the Christmas Specials.  And before you ask, yes, I did recently buy two Dr. Who posters.  I got the Van Gogh Exploding Tardis poster because it's arty and yet sci-fi at the same time and I got the "Everything I Know In Life I Learned From Dr. Who" poster because I thought it was funny and it had David Tennant on it.  Cutest Time Lord Ever!  But, unlike the posters that decorated my childhood bedroom, these posters are intended to decorate the walls of my home office.  Adults show off their interests in their office.  Children use bedroom walls because that's the only space in the house upon which they can express themselves. 

Van Gogh's Exploding Tardis:
 Starry Night Meets Time And Relative Dimension In Space

But, I digress.  I watch the show devotedly, for the three months that it is on and then my focus shifts to some other show.  Cable T.V. shows are perfect for my intensive, yet short attention span.  They run for a season (winter, spring, summer, or fall) and then they go on hiatus for 10 weeks before returning with the second half of the season.  It lets me get really into a show and then, just when I'm about to lose interest, it's gone for a while.

Am I the only one who does this?  Is there anything that you have OCD limited by ADD for?