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Common Developer Mistakes

Recognize habits that create hidden risk, complexity, and stalled growth.

Topic library

Overengineering earlyRewriting before understandingIgnoring failure statesUsing production as the test environmentLogging sensitive dataRetries without idempotencyOptimizing without measurementTreating review as approval onlyAbstracting after one exampleMaking everything a microserviceHiding uncertaintyBecoming a single point of knowledgeConfusing activity with impact

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Practical starting points for the highest-value topics.

Overengineering early

Complexity is added for imagined futures while current requirements remain unclear.

  1. State today's requirements and likely near-term change.
  2. Choose the simplest design with a clear extension point.
  3. Measure the constraint before introducing infrastructure.
  4. Record what signal would justify the more complex design.

Key idea: Good architecture preserves options without implementing every option.

Rewriting before understanding

A replacement begins before existing behavior and constraints are known.

  1. Inventory users, integrations, undocumented behavior, and operational history.
  2. Add characterization tests around critical behavior.
  3. Identify whether the problem is boundaries, tooling, performance, or maintainability.
  4. Prefer incremental replacement with measurable checkpoints.

Key idea: Old code often contains requirements that are not written anywhere else.

Becoming the only expert

Being indispensable feels valuable but creates risk and limits growth.

  1. Document common operations and decisions.
  2. Pair on difficult work and rotate ownership.
  3. Create safe opportunities for others to make changes.
  4. Move from answering every question to teaching diagnostic approaches.

Key idea: Senior engineers create capability, not dependency.