Appetites instead of estimates

Set time based constraints rather than scope based constraints, then see what you can deliver in that time.

Estimation is hard. Given a fixed scope, most teams will underestimate how much time it takes to get something done. Then once you get towards the end you'll say "ok, just one more week. Or maybe two, or three".

I've found great success both personally and with teams I work with setting a fixed date, then working to ship the best thing we can in that time.

For me, it might be that I have 2 hours to write a proposal for a project that I want the business to fund. For the team, it might be a stakeholder demo in 4 weeks.

This post from Jason Fried really nails the sentiment by comparing it to a holiday:

A appetite is like a budget. Not "we think it'll take 4 weeks" but "we're only giving it 4 weeks." That's all we've got set aside for it. Then the team tasked with the work has to get creative and figure out the 4 week version of that feature. There is no 6, 8, 10, or 12 week version when the appetite is 4 weeks. Just like there's no $7,000 vacation when you only can afford a $2500 one. And you know how that ends up if you overspend.