You can ask 10 people that question and get 10 different answers.
First off is your DD barrel chrome lined?
If it is dont worry too much about break in. The chrome is so hard that unless you are into running an abrasive (JB Bore Paste or the like-NOT reccommended BTW) down a new barrel you arent going to do anything. Just clean it after 20 rounds or so for the first hundred.
Now if it is not chromed that is a bit different. I will generally wet patch/brush/dry patch after every shot for the first 20 rounds. After 20 rounds I will stretch it out to every 5 rounds before I do the clean routine for the next 20-30 rounds.
After that if it is a accuracy critical firearm such as a bolt gun or precision semi I generally wont clean it until I see a degredation in group size.

Some good reading here:

http://www.larrywillis.com/Barrel.html
http://www.rifle-accuracy-reports.co...-break-in.html
http://www.riflebarrels.com/support/...aintenance.htm