I've read articles in many different places about jelqing . Most all info about how to do it states that you should resist the urge to ejaculate during the excercise and for a while afterwards. But the reason given is to "Teach control". Well, if that's all it's good for, as long as you already clocked in your time working out for that session and you already know how to control yourself, what harm is there in letting it fly? Save all that bio-chemical hormonal mumbo jumbo, please.