Back in the early 80's, I worked at a fireplace / wood stove retail store in Colorado. The proprietor was an immigrant stone mason who had built hundreds of chimneys during his career, plus several masonry chimneys in his sprawling store. In addition to the masonry chimneys, there were several metal insulated chimneys.
We heated the store using only wood heat. Every section of the store had either a wood stove, fireplace insert or a decorator fireplace.
I asked him one day how often he cleaned his flu's. He replied - never. (parts of his store had been constructed for 25 years). He said that on all the chimneys with the air tight stoves - he purposely starts a flu fire (raging fire in the fire box with the doors open), and as soon as he hears the flu catch fire (kinda sounds like a jet roar) he would shut the doors / turn the air control off, and in 30 seconds the combustion air was totally consumed, all flames extinguished. Then he would crack open the air control to put the stove on low heat and head to the next stove to repeat.
He went on to say, that if done often enough it keeps the flu clean as a whistle.
(On the decorative fireplaces, those were never burned enough to worry about. Plus he would rotate stoves all of the time - so those chimneys were "cleaned by fire" when an air tight stove was installed. )
They actually had two retail locations. After I was trained, they sent me to manage the other store, and I was instructed to do the same. I must say, it is a scary feeling to let the fire rage to the point you here the chimney catch, but a fire does need oxygen to burn. After a while it became second nature.
DISCLAIMER: He was a professional who knew exactly what type of chimney he had, and had either personally installed or supervised the installation of every chimney (and stove). Plus, he maintained the stoves, replacing gaskets, etc and knew if he turned the air dampers off, it would completely shut off the oxygen supply. DO NOT TRY THIS.
I will say that I do the same with my stove in my building. Oh, not every time I use the stove, but maybe every 10th time. My flue (insulated metal) is clean as a whistle.
One key point, the flu / chimney systems were inspected yearly to make sure no cracks, obstructions or other hazards were present.
And one other tidbit, you can clean the glass with easy off oven cleaner to get rid of the soot build up.
