Last year was my first year of burning and I used about 8 face cords of good seasoned wood. I have a straight stack all the way up with no bends. Should I clean it this year or can I go another season? The reason I ask is because there is a guy at work that has been burning for awhile and he says he cleans his stack every 20 face cords or so....He also has a straight stack with no bends. Thoughts please...