Swept 3 flues at a 1890s house in Providence and the last one had 6 feet of packed creosote, customer said the guy before me was there 2 months ago | Chimney Sweeps - Vivisector
Nobody ever checks the flue size against the appliance. Old houses in Providence got those big open fireplaces, but somewhere along the way somebody shoved in a wood stove or a furnace with a smaller outlet. When the flue is way oversized for what's hooked up, the smoke cools off before it gets out the top. Cool smoke dumps creosote fast. Two months can do that if the setup is wrong. The sweep before you may have done a fine job and the house still clogged itself back up.