3. The “Istikhlaaf”

If power was taken from its rightful owners in the story of Saqifah, and according to the second caliph, the allegiance given in that event was on the spur of the moment and could have had dangerous outcomes, why was the same mistake repeated after the first caliph? Didn’t the Muslims have enough time to ‘figure things out’ when it was time to choose the next caliph?