LLM velocity multipliers seem to decay as the codebase grows
I've been thinking about how LLM coding costs scale across the life of a project, and I'm not sure the way we usually frame it holds up. Greenfield is where the velocity multiplier looks the best — small context, clean abstractions, low blast radius — and that's also where the per-change token cost is lowest. Both of those move in the wrong direction as the codebase gets bigger and harder to reason about. Each change pulls in more files, more constraints, and more historical decisions the model has to re-discover. The bill goes up while the speedup goes down. I'm guessing this gets worse on projects built primarily by LLMs, because the patterns the model laid down in the easy phase don't always hold up under the weight of real product complexity, and the inefficiencies are harder to spot when nobody hand-wrote them. That's a hunch, not a finding — I'd want to see real cost-per-feature curves on a few projects of comparable scope before I'd commit to it. But it's the question I keep coming back to when people quote a velocity multiplier without saying what month they measured it in.