The point is for the runner to go from first to third on a single. That's why the hit and run exists—that, and staying out of the double play. It's best called on hitter's counts—1-0, 2-0, 2-1, 3-1, sometimes 3-2. A runner who might not be fast enough for a straight steal takes off, knowing that the batter's swinging at anything, trying to put that pitch in play. The advantage is that an infielder goes in motion when the runner takes off, thereby opening a hole. If a grounder gets through the infield, the runner can usually blow right through second and on to third. And even if the grounder is caught, the runner in motion usually negates the double play.
But it's a must for the runner to take a look homeward as the pitch crosses the plate. He has to see where the ball is hit. If it's on the ground, he pounds for second; in the air, he reads it and possibly retreats. If it's a base hit and he reaches second before an outfielder has the ball, he's booking for third.
The perils of the hit and run lie in the batter missing the pitch. A runner cursed with the slow gene is then on a mission he might not complete, if the defense can grab momentum and trap him. Depending on game situation, the stakes can be high indeed. A hit and run can put an offense into high gear or see the defense seize the day. Regardless of outcome, it's one of the game's richest opportunities and best moments.