Does "Two in a row" rule really work?

It is often said that if you don't get a job after releasing from one it is best to find another one as soon as possible to avoid large employment gaps. In other words, once you are employed you don't have to worry about future gaps because it really doesn't matter if you have one because "two in a row" (having a gap between two jobs) is what really hurts your chances. It is often claimed that "HR people" are really picky about it because "careers advisors" know some cases where people lost their job because they had "two gaps in a row" and being jobless for several months before a job is also really bad.<br><br>Does this rule really exist? It sounds weird to me because if "careers advisors" know cases where people got rejected because of this rule, it means that the job was given to some other person, who also had large employment gap. So this rule doesn't seem to make any sense.