The answer to 'carpet cleaning cleaning frequency' is that most experts recommend having your carpets professionally cleaned every 12-18 months, or more often if you have high foot traffic, pets, or young children in your home. Regular professional cleaning helps remove deep-down dirt, allergens, and bacteria that regular vacuuming can't reach, extending the life of your carpets.
Carpets should also be cleaned whenever you notice increased staining, odors, or a general dinginess. Depending on your household, you may need to clean more or less frequently. Following the manufacturer's recommendations for your specific carpets is also a good idea.