To Longarekel:- I am an full fledged Aschkenazi, with no Sephardi blood from any branch of my ancestry.
May I also bring to your attention a little known astronomical fact, that it takes approximately 7-9 minutes less to get dark around equinox time, than at solstice time. Hence even if 72 minutes was time it takes to get dark around June 21 & December 21, around March 21 {near Seder nite time} & September 21, it takes less than 72 minutes to get dark.