You work the part of the ball that you need to in order to do what you need with the ball you have in hand, on the lanes on which you are bowling.
There is never any "you must always do it this way". NEVER! Anyone preaching such should be immediately ignored, including Randy.
Unless he has another hour to explain what you personally should do, I'd ignore Randy's TV lessons. A 30 second lesson will always be worse than useless without detailed follow-up analysis and discussion. This is solely an entertainment section of the program.
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"None are so blind as those who will not see."