Vague async messages break focus more reliably than time-zone delay.
4 of 5 cited ambiguity as the single worst disruptor. Language: 'vague PR comment', 'walking on eggshells', 'vague PM message broke my focus'. The fear behind the ambiguity was as disruptive as the question itself — once the doubt enters the block, the block is over.
"That vague comment triggered doubt. I spent twenty minutes clarifying, and my deep work was broken."— P01 · async champion