Estimates rot

Estimates are at the heart of traditional project management. We break the work down into tasks, guess how long each of these will take, and build a mosaic in Excel. We’ve gone from a big pile of uncertainty to a spreadsheet that allows us to play with numbers.

Estimates have gotten a bad rep, and rightfully so. Nothing good comes from going down the rabbit hole of extrapolating a projection based on estimates.

They are unstable.
They have a limited shelf life.
They rot.

Estimates are valid for a short time and tightly linked to an individual.

If I do this next week, it will take me three days.

That’s a perfectly actionable estimate.

If my colleague Kim does this task next week, it will take her about two days.

That’s a bit riskier as it requires a great deal of understanding of her skillset. As long as we know Kim pretty well, this is a valid estimate.

This task will take two days, regardless of who does it when.

That’s a nonsensical take, and we know it.

Yet it’s the most common way we use our estimates.

We slap a date on them and hold that to be some objective foundation on which to build our plan.

Estimates rot because the future is uncertain. We won’t know what our product will look like six months from now. Complexity rises. We can’t be sure who will be on our team. People might leave.

Building a long-term plan on such a brittle foundation is asking for trouble.

Estimates only shine when used for short-term planning and comparison.

You can expect Task A to be ready by Friday.
Task A will take me longer than Task B.

Building long-term plans on top of estimates is like buying the ingredients for the fruit salad you plan to make a few months from now.