Doesn't matter if you hang before or after your workout session...and you can have you hanging session last as long as you'd like. If you have time to hang for a couple of hours, more power to you...most people, from what I've gathered, shoot for somewhere around an hour and are gaining from it, but if you could hang twice as long you may gain twice as fast. Length is one of those trick things to predict, b/c there really is no way to overwork with hanging, but yet there's still no way to predict whether or not you'll make fast gains or slow gains...it's all trial and error.