I was taught Jesus did not die on the weekly Passover. But that there's a Sabbath day called a high day that is a special sabbath that can occur on any day of the week, and not just Saturday. I don't know anything more about this. We do all realize we can't get 72 hours from the way most Churches teach it.
Yes that High sabbath is the first day of unleavened bread.. That was why they where rushing to bury Jesus because they could not leave His body hanging on the cross on a sabbath because that was considered a curse.. The 7 days of unleavened bread start the day after Passover each year .. Both the first and last days of that 7 day period are High sabbaths.. These High sabbaths are linked to dates .. Not days of the week.. The first day of unleavened bread is always on the 15th of nisan the day after Passover..
Of course you can get 72 hours of you know how the week went..
Jesus was executed on a Wednesday the 14th and was buried just before sundown the start of the 15th Thursday.. Then He fulfilled the prophecy of Jonah by rising from the dead at the start of the first day of the week.. So Jesus was raised from the dead on Saturday sundown.. So from Wednesday sundown to Saturday sundown 3 days and 3 nights ,, 72 hours..