In a famous study, about half the people counting passes missed a person in a gorilla suit. Focus has a cost.

Attention works by leaving things out. Concentrating hard on one task means other things can cross the room completely unregistered, and you will not sense the gap, because missing something feels like nothing at all. Being focused and being well informed are two different states, and the first one quietly costs you some of the second.

When something matters, build in one deliberate look around: reread the whole question, scan the far side of the field, ask what you might have cut out. Do it before you commit rather than afterwards. Treat the blank spots as a price you paid, not proof there was nothing there.