That's not a rule. And it is irrational, because just like now, and previous generations, there is a diversity and conflicting understandings of the text in every generation.
In Daniel 12, the understanding of the book, is sealed from understanding until the time of the end. Time of the end is indicated in the text when travel means and knowledge have been increased.
Jesus rode into Jerusalem on the donkey, hailed as the messiah. 4 days later he was crucified ending the 69th week. And the beginning of the gap to the 70th week beginning.
In the gap, forty years later the temple and city was destroyed, and the Jews sent into exile to the nations.
In the gap, on May 15, 1948, the Jews, abeit not all, have returned to their homeland, 1948, May 15, a nation born in a single day, fulfilled in Isaiah 66:8.
In the gap, 1967, the Jews retake Jerusalem, and make it their capital.
The parable of the fig tree goes into effect.
The 70th week will begin, before that generation passes away, ending the gap. And when Jerusalem and the Jews embrace the gospel of salvation, fulfilling Daniel 9:24.