How often your task estimates end up being accurate?View other answers to this thread
I voted for "From time to time", since estimates based on planning sessions are dependent on the team member and their role. However, I would recommend thinking "shirt sizes" rather than "hourly". Also, review the past few sprints. I find this extremely effective for me in recognizing patterns within different workflows, which basically dictates what's worked in the past for similar issues (relative to the person that they've been assigned to.)
On a personal level, I would actually vote "Quite often". Because there's no guessing game involved, and I'm fully aware of other issues that life might throw me, which a Scrum Master would not be aware of.