Sure, it's necessary if you want to get dehdyrated and wake up the next morning with a hangover.
Not drinking after 2pm, taking 4 doses of epsons which IS dehydrating and not drinking anything untill 10am is a total of 20hrs without water. Even on the box of Epsons it will tell you how it "draws water into the intestines", meaning it's probably sucking it up out of places it should be. I really don't even understand how anyone can recommend that. It's the main reason "nasuea" can be expected the next morning.
I keep downing water for like an hour up to the OO (Olive-Oil) mixture just so I don't have to run to the bathroom after taking it.