What is the length of The Secret Armory of General Knoxx?

Well, I think the subject speaks for itself.  I just downloaded this DLC for Borderlands and finished both the original title as well as The Zombie Island of Dr. Ned.  So, how long is it?

It didn't take me long to get through the main stuff.  A lot of time gets eaten up from all that driving.
 
Still have to kill Crawmerax though (Damn that purple lobster thingy)

Pretty long considering the fact that you have to drive everywhere, which seems to take up a large fraction of your time.

OK...how about an actual number though?  Like a rough estimate of total hours spent?

I remembered this term from a dream I had and then again just now.
 
I must of heard the term from my granddad who served in the air force in world war 2 - thanks.

took me a good 10 hours for the main quest and a few side missions, so a normal mans 5-7. 
the DLC only really opens up after the main quest-line is done.

My first time playing through it took me about 11 hours finishing up the main quest and most of the side quests, and that was across several play sessions, so there was a bit of driving involved, and a lot of fighting in between. Some of the quests in general just take awhile to do simply because when you start out, it's pretty damn difficult and some firefights can last for a good long time. That was all without starting the Crawmerax quest, Circle of Duty, or the Marcus missions.