I was told that the reason was to purge the lines of any liquid gas that may have been in the line. When it did the second cycle only gas should be in the line. Does it need it, probably not. My P-120 starts perfectly every time without going through that process. And I never saw the start reliability increase with this sytem. It still depended on the right pressure in the gas cannister, the right temp, the right battery voltage, the right parameters set, and the current phase of the moon.