Best practice is comforting. It is the slide everyone nods at, the benchmark the board asks for, the reassurance that you are doing what the good companies do. It is also, quietly, a ceiling.
The trouble is in the definition. Best practice is the average of what everyone else already does. Copy it well and you reach the middle of the pack. You cannot copy your way past the people you are copying.
When you adopt a best practice, you inherit two things. The visible part is the tactic itself. The hidden part is the set of assumptions baked into it: the kind of business it was designed for, the market it assumed, the constraints it took for granted. Those assumptions are rarely yours.
So you import not just the herd's method but the herd's waste. The funnel that works for a venture-backed app is overhead for a trades business. The reporting stack that suits a thousand-person company is a tax on a team of ten.
First principles ignores how it is usually done and asks what actually creates value here, in this business, in this market, under these constraints. It is slower at the start and far faster in the end, because it builds the right thing once instead of the average thing forever.
A worked example: a competitor runs a particular discount cadence, so the best-practice move is to match it. The first-principles move is to model your own unit economics and discover the discount is training your best customers to wait. Same market, opposite conclusion. Only one of them was looking at your numbers.
This is not a case for reinventing everything. For solved, low-stakes, commodity problems, best practice is exactly right. Use the standard security setup. Follow the accessibility guidelines. Do not hand-roll what the world has already settled.
The discipline is knowing the difference. Spend your best-practice budget on the commodities, and reserve first principles for the few places where the edge and the leak both live: pricing, the core product, the way the work actually gets done.
Every build I take on starts from first principles for one practical reason. The gap that is worth closing is, almost by definition, the thing best practice missed. If everyone could already see it and fix it with the standard playbook, it would not still be costing you money.