Dryer vent cleaning
The one that's genuinely about safety.
Dryer vent cleaning is the service most worth doing on a schedule, because lint buildup in the vent is both an efficiency drain and a real fire risk. If your dryer takes two cycles to dry a load, the vent is a likely culprit.
It's a quick job with a clear safety payoff.
The Knoxville job that is actually about fire
This site already treats dryer vent cleaning as the service most worth doing on a schedule: lint in the vent is a fire risk and an efficiency drain, and a load that takes two cycles is the usual homeowner clue. That is a different standard from air-duct cleaning, which waits for a real cause rather than a coupon. A referred provider serving Knoxville clears the vent; this site does not send a crew.