Go as long as you can knowing you will roll back into a 72, if you feel good keep going. But don’t use those extra fasting hour to eat more then you’re normal break/or for more time. If you feel good no harm going an extra day, or extra hours etc. if my 72 ends on a Wednesday but my friends want to get together Friday night I’d rather extend my fast and extra 2 days and enjoy myself on the social engagement etc.