You entirely listen to your body. I often have trouble breaking 3 days but last time went 4 1/2 and could have gone longer.
I haven’t done a hard dry fast yet but I’ve noticed my weight will pick up after a long shower. So I definitely think there is some merit to the idea.
My skin looks great on a fast too. I don’t think there is anyway to do it wrong, just listen to your body it’s so important.
I sometimes have very very minor discomfort that goes away after a bit. But if I ever feel actual discomfort or pain I break immediately. Only once have I ever had pain where my lower backbstarted hurting.