THe ability to throw a 300 comes from a sound knowledge of your own game, ie, how you react under pressure, and what adjustments you need to make in that situation.
What I mean by that is, whether or or not you make your best shot under pressure, whether or not you get fast (like me) or slow, whether you trust it or not etc. I know that when I have 11 in a row, I need to move 2 boards left cos I get a bit fast cos of the adrenalin and as a result the break point is slightly delayed and the ball wont hook quite as much.
Finally after many years of practice I have a trust of my technique and ba sound knowledge of how i react under the gun. Even so, i have more misses after 11 in a row than successes, but I usually get the ones that really count, as in Manhattan SuperClassic in 1999.