My double is two away from me What am I?

In English, but also in Math, 'Eleven plus two' Equals?

I hide in choices u haven’t made, I vanish the moment a path is laid. I can haunt u, help u, or keep u still, I’m the shadow that forms when u test your will. I’m the space between maybe and done, Name me, and you’ll see I was more than one.

A state of knowing reached with no deliberation A product of the subconscious? Often improved with experience

There is one in a second, none in a minute, two in one hour, but none in half. What am I?