A chimney in Portland had a massive creosote drop after just one heating season
I cleaned a chimney in the Laurelhurst neighborhood last fall that was pretty normal, maybe a quarter inch of buildup. Went back for a check this spring and found over an inch of hard, glazed creosote in the same flue. The homeowner had switched to burning green, unseasoned wood from a local lot to save money. It completely changed how I explain fuel quality to new clients. What's the fastest buildup you've ever seen from bad wood?
Read a case study where a guy burned pallet wood for one winter. Not the treated kind, just cheap scrap. His liner was a solid block of creosote by February, like a clogged artery. Had to be replaced entirely. That stuff is basically fast food for your chimney.