Five Step Engineering Process

1. Make your requirements less dumb - question requirements even from a smart person
2. Try hard to Delete the part or process, if you’re occassionally not adding back in, you’re not deleting enough!
3. Simplify or Optimise - biggest mistake optimise something that shouldn’t exist
4. Accelerate cycle time (improve iteration speed)
5. Automate

Elon admits he made the mistake of going backwards.

See also Elon Musk’s Six Rules for Tesla Employees.