Lean Six Sigma is a well-established quality management method. It combines Lean principles (eliminating waste) with Six Sigma (reducing variability).

When properly applied, Lean Six Sigma leads to:

• Improved operational performance,
• Reduced costs,
• Increased customer satisfaction.

However, many projects fail or fall short of their goals. Why? Because several key mistakes are often made. Here are the five most common ones — and how to avoid them.

1. Poor Problem Definition

A Lean Six Sigma project starts with the Define phase. This step is critical, yet often rushed or overlooked.
Common mistake: Launching a project based on vague complaints or gut feelings, without solid data.
Example: “Our delivery times are too long” — without knowing how long, under what circumstances, or why.
Consequences:

• Blurry scope,
• Time wasted on secondary issues,
• Disappointing or off-target results.

How to avoid it:

• Clearly define the problem using data, facts, and dates.
• Gather the Voice of the Customer (VOC) to understand real expectations.
• Set project goals using the SMART method (Specific, Measurable, Achievable, Realistic, Time-bound).
• Use the SIPOC model to map inputs, outputs, and processes involved.

Takeaway: A well-defined problem is half solved.

2. Failing to Involve Stakeholders

A Lean Six Sigma project involves multiple layers: leadership, frontline staff, internal clients, etc. Without their engagement, the project risks stalling.
Common mistake: The project leader works in a silo without consulting those directly involved.
Result:

• Misunderstandings,
• Resistance,
• Difficult or failed implementation.

Why does this happen?

• Lack of time,
• Fear of conflict,
• Overconfidence in a purely technical approach.

How to avoid it:

• Identify key stakeholders early on.
• Hold collaborative workshops.
• Collect regular feedback at each step.
• Lean on a project sponsor to carry the message to upper management.

Good practice: Involving teams helps uncover hidden obstacles and increases ownership of the solution.

3. Jumping to Solutions Too Quickly

A classic mistake: trying to solve a problem before analyzing it. The intention is good, but the method is flawed.
Common mistake: Acting on a suspected cause without a thorough analysis.
Example: “Let’s just hire one more person” — without verifying whether staffing is the real issue.
Risks:

• Wasted time,
• Ineffective or temporary fixes,
• Problem reappears in another form.

How to avoid it:

• In the Analyze phase, take time to study historical data, trends, and variations.
• Use tools like:
  • Ishikawa (cause-and-effect) diagrams,
  • The 5 Whys technique,
  • Pareto analysis (80% of effects come from 20% of causes).
• Test your assumptions against the facts.

Tip: Avoid rushed decisions. Base solutions on solid analysis.

4. Underestimating Resistance to Change

A technical solution may be brilliant — but if it ignores human factors, it can fail.
Common mistake: Focusing only on processes, not people.

Why is this common?

• Change is uncomfortable,
• Habits are deeply rooted,
• There’s a false belief that logic alone will convince people.

Consequences:

• People don’t follow new procedures,
• Old habits return,
• Team morale drops.

How to avoid it:

• Support change with a clear communication plan.
• Offer targeted training.
• Address fears and listen to objections.
• Involve those affected in decision-making.

Best practice: Appoint “Lean ambassadors” in each department to spread a culture of improvement.

Reminder: People matter just as much as processes.

5. Failing to Measure Long-Term Impact

Too many Lean Six Sigma projects end once a solution is implemented. But a finished project isn’t always a successful one.
Common mistake: Not verifying whether results are sustained over time.
Consequences:

• Backsliding into old habits,
• Loss of credibility,
• Wasted effort.

How to avoid it:

• Establish a control plan with performance indicators (KPIs).
• Assign responsibility for ongoing monitoring.
• Schedule regular follow-up reviews.
• Automate data collection when possible.

Example: If the goal was to reduce order processing time, keep tracking that metric monthly.

Takeaway: The goal isn’t just change — it’s sustainable improvement.

Conclusion

Lean Six Sigma can transform your processes, teams, and outcomes. But its success depends on a rigorous, structured, and people-focused approach.

By avoiding these five common mistakes, you increase your chances of project success — and build lasting continuous improvement.

Remember: It’s not the method that guarantees success — it’s how you apply it.

Key Takeaways

• Don’t skip the definition phase — it shapes the entire project.
• Base decisions on solid data, not assumptions.
• Involve all relevant stakeholders from the start.
• Analyze before taking action.
• Support people through change with communication, training, and dialogue.
• Measure and track results over time.
• Lean Six Sigma is more than a toolbox — it’s a continuous improvement mindset.