To accurately reduce cost of goods sold (COGS), analyze total cost, including assembly labor, not just individual component prices. A more expensive prefabricated part, like a $1,500 wiring harness, can slash total costs by eliminating $6,000 worth of manual labor time, but requires looking beyond departmental budgets.

Design for Excellence goes beyond just manufacturing costs. Consider the entire product lifecycle, including serviceability. A design that's easy to assemble but difficult to service in the field (like using a blind screw on a replaceable part) increases the total cost of ownership and harms the customer experience.

When screw lengths differ by only a few millimeters, assemblers can easily use the wrong one. This may seem to fit correctly but results in insufficient thread engagement, compromising the product's structural integrity, especially under stress like thermal cycling.

The conventional wisdom that you must sacrifice one of quality, price, or speed is flawed. High-performance teams reject this trade-off, understanding that improving quality is the primary lever. Higher quality reduces rework and defects, which naturally leads to lower long-term costs and faster delivery, creating a virtuous cycle.

A key lesson from SpaceX is its aggressive design philosophy of questioning every requirement to delete parts and processes. Every component removed also removes a potential failure mode, simplifies the system, and speeds up assembly. This simple but powerful principle is core to building reliable and efficient hardware.

LEGO ensures all its global factories are exact operational and physical copies. This extreme standardization means an employee from any factory can transfer to another continent and be fully productive the next day. This "rigidity," as the CEO calls it, provides enormous executional power and flexibility.

Designers should consider the human operators and machines that will assemble their product. By making choices that simplify manufacturing—providing clear instructions and avoiding known difficulties—the process becomes smoother and more efficient, akin to 'riding a bike downhill.'

The default instinct is to solve problems by adding features and complexity. A more effective design process is to envision an ideal, complex solution and then systematically subtract elements, simplify components, and replace custom parts. This leads to more elegant, robust, and manufacturable products.

Zipline's 50% cost reduction for its next-gen aircraft wasn't just from supply chain optimization. The primary driver was a design philosophy focused on eliminating components entirely ("the best part is no part"), which also improves reliability.