The “Home Depot” problem
It always takes one extra trip to Home Depot to complete any weekend home improvement project.
The ”Home Depot” problem is an example of the Planning fallacy.
We assume that tasks will go as planned, but when you start that drywall fix, you realize that something else needs fixing or a better tool will make the job easier. And because of this, you make more trips than expected to your local home improvement store. Because ultimately, your goal to have a better home guides your actions as you negotiate impediments along the way.
Agile Maxim #1 – “It is in the doing of the work that we discover the work that we must do. Doing exposes reality.” – Woody Zuill
Scrum teams actively develop their planning capabilities because we know that plans are fragile to reality.
Scrum teams engage in Sprint Planning to agree on the Sprint Goal, synchronize daily to check progress against the Sprint Goal, mitigate process and quality risks via the Retrospective, and get user feedback on the Product Increment. The Product Goal further guides the integration of sprint-level product increment feedback toward the long-term aspiration of the product. These feedback loops inform the team to acknowledge and act on the shared reality.
The beauty of XP, Scrum, and agile approaches is that they have circumvented the need for plans. Instead, they use feedback loops to become better informed on the current state and use goals to decide on the next steps. It is a robust response mechanism that helps overcome the human limitations of making reliable predictions and keeping hubris in check.
The need for estimates handicaps plan-driven development approaches. These approaches can only operate with Story Points or task hours. They are fragile to estimates.
Alignment on shared goals and the ability to plan and replan is necessary, whereas estimating is not. Some agile teams value collaborative estimating practices, while others drop all estimates. The proponents of plan-driven methodologies will consider the lack of estimates a weakness. But if you ask them:
How many Home Depot trips does it take to complete a weekend project? – they might come to see it differently.