The “50% time horizon” feels most actionable when you pair it with an expected-value model. For a given task: EV ≈ (human_time_saved × $/hour) − (p_fail × cost_of_failure) − (iteration/oversight cost). A model crossing 4h-at-50% might be hugely useful for low failure-cost work, and still net-negative for anything where rollback/debug is expensive. The missing piece is how p_fail scales with task length + how recoverable failures are.

Yeah--it's difficult to go from a benchmark involving the model attempting things alone to the effect assisting people on real tasks because, well, ideally you'd measure that with real people doing real tasks. Last time METR tried that (in early '25) they found a net slowdown rather than any speedup at all. Go figure!