About every 3 days for my little stove. Sometimes sooner depending on how much and what type of wood burned.
Depends on the temps, but it's about every 4-5 days here too. Although I don't like a deep ash bed so I could probably go for a week. Seems like the deeper the ash bed, the longer it takes for coals to burn down and less room for a reload. Cleaned all of the ashes out yesterday and it's purrin' like a kitten right now.
I checked my double walled chimney for the first time this season, and it's clean as a whistle. Very happy with this stove.
You have to "Shovel" out ashes??? Really, the most underrated benefit of the Woodstock PH, is the giant and easy to use Ash pan. No shovel needed.