In the Limitless pilot, when evading the police in the subway, Brian jumps on the tracks, calculates that there's an 80%-90% chance the train will stop on time if the driver sees him, and he kept standing there.
Once the train stops, he ducks under and crawls to an abandoned line.
Why would he not lie down right away, knowing there was a non-zero chance the train would hit him?
He needs the train to stop
It isn't just to enhance the suspense for the audience. His brain on NZT is formulating an escape plan several steps ahead. He knows he can get to the abandoned line but he can't do that while the train is moving. And, he can't do that without the police seeing instantly where he is going if there is no train at all there.
So he isn't really taking a risk. He knows where the train will stop and he needs it to stop there to maximise the chances of getting away from the police unseen (or at worst delaying them while they work out what happened.)
This wouldn't work if he lay down and failed to stop the train. The brain on NZT is pretty smart.
