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overproduction is the worst waste of all

Lean Principles and Waste Elimination

7

Wastes

TIMWOOD or DOWNTIME depending on the memory aid

Pull

System

Work is pulled when capacity exists

5S

Workplace

Sort, Set, Shine, Standardize, Sustain

every process leaks · spot the seven, plug the worst

The 7 Wastes · TIMWOOD

T

Transport

→→→

Moving files, parts, or people between steps that shouldn't need movement.

I

Inventory

▦▦▦

Stockpiles of unfinished work, untested code, undeployed releases.

M

Motion

People walking, reaching, clicking through layers to do one task.

W

Waiting

Person waiting on approval, ticket, build, review, next shift.

O

Overproduction

Building more than the customer asked for. Worst waste of all.

worst
O

Over-processing

✦✦

Polishing what the customer didn't ask for. Gold plating belongs here.

D

Defects

Bugs, rework, scrap, wrong shipments. Every defect doubles cost.

how to read this

  • TIMWOOD is the memory hook — one letter per waste.
  • › Walk any process with this list and you will find at least three wastes within 10 minutes.
  • Overproduction is the worst — it hides every other waste inside piles of unneeded work.
  • › Lean asks: "would the customer pay for this step?" If no, it's waste.

Exam Traps

Defects are waste

Rework is considered a waste under Lean. Preventing defects is cheaper than correcting them.

Overproduction is the worst waste

Building more than the customer needs creates inventory, cost, and hides other problems. Lean hates overproduction above all.

Value stream mapping exposes waste

VSM shows where time is spent, where queues form, and where waste hides. The exam tests awareness of this tool.

Pull, do not push

Work enters the system when there is capacity. Pushing overloads the system.

Waste is everywhere

Seven categories. Learn to spot them in every process.

1
Overproduction

Making 20 sandwiches when you have 5 customers. Stale bread, wasted money.

2
Waiting

The slicer is broken and everyone stands around. Waste of time.

3
Transport

The deli meat is stored in the basement. Every sandwich means a trip downstairs.

4
Defects

A wrong order means a new sandwich. Rework costs double.

TIMWOOD or DOWNTIME. Seven wastes, every process.
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Reviewed by Chris K., PrepSolution Content Editor, Project Management
Sources verified against PMI 2026 standards
Updated May 2026