That is a true statement. We tried for many years to have a second child, even using one of those multiple birth possibility prescriptions as an assist for the problem. Nothing happened. Then years later, after giving up, my father-in-law passed away, and bingo, we found out we were expecting child #2 - 14 years after the 1st one. The timing was downright eerie.
Again we are soulmates! I had one starting HS and bam, then two came withing 15 months ;)