Is There Room to Run?
Measure the distance to the nearest opposing level before you take the break. A breakout in the right direction still loses if the first obstacle sits inside your first target.
What is measured here and what is not. The runway rule is arithmetic and order-flow reasoning — we have not tested it on a large sample, so treat the thresholds as a discipline rather than as calibrated odds. What is measured, on 489 breakout attempts across 490 SPY sessions: 75% of attempts closed back inside the range, and among the ones that held, the median best price within ten minutes was 0.72 range widths. That figure is the reason 0.25W is used here as a default first-harvest target — it is comfortably inside what a working breakout usually delivers.