When hiring senior engineers, the crucial test is whether they can build. This means assessing their ability to take a real-world business problem—like designing a warehouse system—and translate it into a tangible technical solution. This skill separates true builders from theoretical programmers.

When senior engineers move away from hands-on coding, their understanding of the system becomes abstract. This leads to designs disconnected from reality, and they lose the trust of their team, who see them as out-of-touch architects without "skin in the game."

A senior engineer’s greatest asset is their ability to recognize patterns from past projects—what worked and what failed. Junior team members can accelerate their work by asking seniors if they've encountered similar problems, providing a validated starting point and avoiding paths known to be dead ends.

When scaling to production, the biggest pitfall is the implicit knowledge held by the original design team who unconsciously fill procedural gaps. To succeed, involve someone with a manufacturing background but no project history to rigorously review procedures and expose these unstated assumptions before scaling.

Design leaders must rapidly switch between high-level strategy and deep, hands-on critique. If they're not a strong practitioner, they lose credibility and can't effectively course-correct work, leading to quality issues discovered too late in the process. Operational skill alone is insufficient.

The most effective product reviews eliminate all abstractions. Forbid presentations, pre-reads, and storytelling. Instead, force the entire review to occur within the actual prototype or live code. This removes narrative bias and forces an assessment of the work as the customer will actually experience it.

Mentoring's value increases when done outside your direct org. It becomes a two-way street: you learn about other parts of the business, and you can plant seeds of influence and better engineering practices that can grow and spread organically throughout the company.

To ensure a smooth transition from development to production, an operations or manufacturing SME must be part of the design process from the start. Otherwise, products are developed without manufacturability in mind, leading to expensive, reactive fixes and subjective quality control during scale-up.

A senior engineer, confident in their design, submitted it to a review at a junior engineer's request. The junior engineer found a critical flaw that would have made the product unusable. This underscores that tunnel vision is universal and diverse perspectives in reviews are non-negotiable, regardless of hierarchy.