A reading measure is for reading. Prose wants 68 characters; a board of five lanes wants the viewport. When a lane layout is nested inside the prose column and given overflow-x, the right-hand lanes are reachable only by a horizontal scroll most people never think to try — and they are, in practice, invisible.

This is not hypothetical. Shipped exactly this way, the two hidden lanes were Needs review and Done — and every run that failed landed in Needs review. The states most needing a person were the only two that could not be seen, at every viewport width.

The rule: any layout whose items are states, lanes, or columns must break out of the reading measure and span the container. If items still exceed the viewport, they must degrade by reflowing — stacking into sections, or collapsing to a filterable single column — never by scrolling silently. Where a horizontal scroll is genuinely warranted, it must show its affordance: a visible edge fade, a count, or paging controls. Audit this by asking not "does it fit" but "which state is off-screen, and what happens to work that lands there".