A person doesn't need to sweep after every cord if they know what they're doing, know their stove and the condition of their wood. If someone has marginal wood, is getting a lot of build up in the stove/pipe then its a safe bet to sweep more often until things get dialed in. Once a season is the "norm". When you have 4 chimney fires in 5 months.....you're doing something wrong. If you indeed a had a chimney fire, that is why your pipe looked clean. Everything was burnt off. But you're playing with fire....literally having that many chimney fires already.I have a 5 month old VC Defiant. We have burnt about 5 full cords so far. I believe we had 4 chimney fires but I managed them myself. Sounds like a freight train and the whole house rumbles. After the 4th chimney fire I got a chimney sweep with a camera and he says the pipe is immaculate. With all that said, why does a person need to sweep after every cord? Or is that a personal preference? I did buy a chimney pipe cleaner but it says to do it once a year.