Assuming is quick. Asking takes one extra sentence and saves you a week of being wrong.

Assumptions are fast because your brain fills gaps automatically and never flags that it did. The filling feels like knowing. Then you build a week of work, or a whole opinion about someone, on top of a detail that was never confirmed, and the correction costs far more than the question would have.

Catch yourself at the point where you are about to proceed on something you were not actually told, and ask the one sentence. Did you mean this or that. Am I right that this is due Thursday. The small awkwardness of checking is the cheapest thing in the whole exchange.