5 Common Estimation Session Mistakes and How to Avoid Them
Estimation sessions are fundamental to agile planning, but when poorly conducted, they can be an enormous waste of time. Here are the five most common mistakes and how to fix them.
1. Estimating without sufficient context
The problem: The team tries to estimate a task that nobody fully understands. The result is random guesses and unproductive discussions.
The solution: Before estimating, ensure that:
- The user story has clear acceptance criteria
- The team had time to ask the Product Owner questions
- Any technical dependencies are documented
If nobody feels comfortable estimating, the task needs more refinement — not a forced estimate.
2. Allowing anchoring bias
The problem: The most senior developer says “seems like about 3 points” and everyone agrees without thinking. Or the first speaker influences the rest.
The solution: Use simultaneous voting. In Planning Poker, everyone reveals their votes at the same time, eliminating the influence of whoever speaks first. Digital tools like Dev in Poker make this automatic.
3. Sessions that are too long
The problem: Estimation sessions lasting more than an hour cause mental fatigue. The quality of estimates drops drastically after the first 45 minutes.
The solution:
- Limit sessions to 45-60 minutes
- Estimate a maximum of 10-15 items per session
- Take breaks between estimation blocks
- If an item generates too much discussion, mark it for refinement and move on
4. Estimating in hours instead of complexity
The problem: “How long will it take?” is the wrong question. Hours vary by developer, their familiarity with the codebase, and daily interruptions.
The solution: Estimate relative complexity using story points. A 5-point item is always more complex than a 2-point item, regardless of who will implement it. Sprint velocity (points delivered) naturally converts points into capacity.
5. Not revisiting previous estimates
The problem: The team estimates, delivers, and never looks back. Without feedback, estimates never improve.
The solution: Reserve 10 minutes in the retrospective to compare estimates with actual results. Ask:
- What did we underestimate and why?
- Which tasks took longer than expected?
- Is our understanding of “3 points” calibrated?
This feedback loop is what transforms estimates from guesses into reliable predictions.
Bonus: estimating unknown tasks
When the team faces a new technology or unknown domain, consider:
- Technical spike — allocate time to investigate before estimating
- Range estimate — “between 5 and 13 points” communicates the uncertainty
- Risk factor — flag items with high uncertainty and revisit after the spike
Conclusion
Good estimation sessions aren’t about perfect precision — they’re about team alignment and risk communication. By avoiding these common mistakes, your sessions will be shorter, more productive, and your estimates much more reliable.