We ran ours straight through from November without a cleaning. The double wall stove pipe had some build up, not much. I'll snap a photo this evening.
I was a little careless and probably lost as much as I caught-- but tried to save what I could. I'd guess I pulled a quart out of the chimney after 2 months of burning. I should add that this was with some seriously lazy burning habits toward the end of the year- everyone wanted to see how it would burn on low. It is maybe a little shiny and maybe a tiny bit flakier compared with how it used to be. At this point I will be comfortable cleaning the chimney yearly and the stovepipe mid winter but will monitor the first year.