The detachment of individual deliverables from estimates is definitely an improvement but I honestly think the notion of even hand waving estimation is a bad idea with harmful consequences.
Measure velocity for sure. Keep track of what kinds of things harm or improve it. But the absolute worst thing you can do is find an abstraction like tshirt size or rolling average and superimpose it on discreet work. You’re going to be wrong. And probably disappointed or disappoint someone else.
My strategy for estimation is:
- It’s tiny and I’m doing it now, I can give you an estimate within an hour margin.
- It’s small, it’ll be done in a reasonable amount of time that no further estimation is required.
- It’s not small and more research/design/planning is required. Any estimate you extrapolate from this is dishonest.
That’s it.
Edit: that wasn’t quite all. “It’s tiny” is reserved for urgent situations that require rapid response and not something I offer outside that situation. For daily work, it’s small or it’s too big to say. Tiny things are too easy to abuse (by managers or engineers) if they’re part of the normal flow.