How often do you shampoo your carpets?

 Just returned home from purchasing carpet cleaner solution. We do not really have a set schedule for shampooing our home, and I'm sure it shows.... LOL.  Right now my son's bedroom carpet smells so bad, and it has to be cleaned ASAP! He apparently spilled chocolate milk in his room, and covered it up with his bedroom floor rug!!! Boys.... {sigh}

 So I am getting ready to shampoo, and was wondering how often do most people actually do it? Just wondering.... ;)

**By the way, there's a bunch of great carpet cleaning and other cleaning coupons available in the Savings Center right now.

 Including one for save $5 off a Bissell Carpet Cleaner rental from Lowe's. {Found under the household category}