Dryer vents should be cleaned once a year on average. For larger households with more dryer use, every 6 months is recommended.
Make sure your vents are in prime condition. Broken dryer equipment can cause loss of efficiency and it can also cause a fire.
Keep birds and other pests from making a home in your dryer vent and causing damage.
Last year there were 16,800 house fires in the us caused by dryers. The number one reason was failure to clean!