The answer to 'how long does dryer vent cleaning last' is that a professional dryer vent cleaning typically lasts 1-2 years before the vent needs to be cleaned again. The frequency can vary depending on factors like how often you use your dryer, the length and complexity of your vent system, and whether you have pets that shed a lot of hair.
Regular dryer vent cleaning is important to prevent lint buildup, which can be a fire hazard and reduce the efficiency of your dryer. Most experts recommend having your dryer vent professionally cleaned at least once a year, or more often if you notice your dryer taking longer to dry clothes or if you can see visible lint buildup in the exterior vent.