zlacker

Try systematically collecting some fine grained data comparing your team's initial time estimates against actual working time spent on each ticket. See what distribution you end up with.

Make sure you account for how often someone comes back from working on a 3-point story and says "actually, after getting started on this it turned out to be four 3-point tasks rather than one, so I'm creating new tickets." Or "my first crack at solving this didn't work out, so I'm going to try another approach."

>>mitthr+(OP)
That's literally what retrospectives are for. You do them at the end of every sprint.

Granted, they're point estimates not time estimates, but it's the same idea -- what was our velocity this sprint, what were the tickets that seemed easier than expected, what were the ones that seemed harder, how can we learn from this to be more accurate going forwards, and/or how do we improve our processes?

Your tone suggests you think you've found some flaw. You don't seem to realize this is explicitly part of sprints.

I'm describing my experiences with variances based on many, many, many sprints.