It's a mystery. With a good result it sounds like. I think that, given the circumstances, it just happens when our minds are not really engaged.

Last year, as I was driving, I was thinking about all the stupid people driving around me like crazy who couldn't drive. I barely made it through an intersection without hitting all the crazy people around me.

In deep thought on the subject I subsequently drove into the curb while turning. I flattened my tire and jammed the rim into the axle so hard I needed a hammer to bang it off.

No more deep thoughts for me.