Subs for me have always lasted for about 8-10 hours. I would usually get uncomfortable before my last dose of the day sort of like a slight comedown before it. The half life doesn't have anything to do with the duration of the effects. Well it does, but what i'm saying is just because the half life is 36 hours doesn't mean your going to get effects nearly that long.
If you already stopped the whole day and dont take any by the next day you might be able to get some effects. But for future reference you'll want to start taking less subs a few days before you plan on getting high. Comming down from 16mg's in a few days seems to quick. If you were on lets say 8mg's a day then went down to 4mg's for a few days, lets say you took 2mg's in the morning you could get high that evening. I've gotten high when I took 4mg's of sub in the morning and then got high at night. I broke through with dilaulaid, oxies and benzos. But I could almost feel the euphoria being held back. The longer you wait the better. Or else it's a waste.