Notes on buildingXXVIII
Compounding goes both ways
The reason compounding is hard to act on isn’t that people doubt the maths. It’s that the daily increment is always below the threshold of noticing.
Nobody chooses to erode user trust. They ship one email that’s slightly more aggressive than the last, and it performs, so the next one is slightly more aggressive than that. Two years later the list is large and dead, and no single decision in the chain looks like the culprit.
The ledgers nobody opens
Three accounts compound in most companies, and typically one is instrumented.
Technical debt is the tracked one — badly, but tracked. It has tickets.
User trust has no ticket. It moves on things that never reach a dashboard: whether the cancel flow is honest, whether the incident post said what actually happened, whether the price changed quietly. It is slow to build, and it doesn’t decay linearly — it holds, then goes.
Culture is the same shape. It is the average of what got tolerated, not what got written down. One person shipping without review, unremarked, is the new standard by the following quarter.
An incident report that names the actual cause is the concrete version. In the moment it costs something real: it hands a competitor a quote, it invites a harder question from a customer, it is strictly worse than the vague version for this week. What it buys is that the next time you say something is fine, someone believes you. There’s no way to buy that quickly, and no way to keep it after one report written to reassure.
Where it breaks
The long view is also the most respectable way to avoid shipping.
“Optimise for ten-year effects” is unfalsifiable in the present tense, which makes it perfect cover. Refactors nobody asked for, a rewrite justified by maintainability, six weeks on a design system for a product with forty users — all defensible as compounding, all indistinguishable from procrastination while you’re inside them.
And compounding assumes survival. A company with nine months of runway does not have a ten-year decision to make; it has a nine-month one. Advice about decades is disproportionately written by people who already cleared the survival filter, which is the same survivorship problem that makes luck advice unreliable.
The honest version is narrower: a small number of things compound, most don’t, and the compounding ones are usually cheap per unit. Writing the incident report honestly costs an hour. Not adding the dark pattern costs a conversion point. Reviewing the pull request costs twenty minutes. None of these are the six-week refactor, and the six-week refactor is the one that gets justified this way.
The test
Ask whether the thing accrues on its own once started, or needs continuous spend. Trust accrues. A design system does not — it decays without staffing.
Then ask what the daily increment costs. If it’s an hour, it is probably real compounding. If it’s a quarter, it is a project wearing compounding as a costume.
Takeaway: optimise for 10+ year effects.