I think they become a necessity at some point. Not only cialis or viagara, but clamping as well. I think you can only make so much gains with just using your hands before you hit a wall. I've made one single quick burst of girth gains during my entire Penis Enlargement career when I went from my starting girth (midshaft) of 5.1'' to 5.3''. After that I've experimented with several different types of programs and exercises with varying degrees of intensity, and I have not gained one tenth of an inch more. Which is really starting to piss me off, since I can't order any ''boner pills'' off the net, and we don't have cable clamps in most of Europe (I think the UK is the only exception). I only do the most intense exercises for girth, but I can never keep up a 100% eretion for more than a few seconds before it diminishes into the 60-80% range. I also never get a post-workout pump anymore, either (can't remember the last time I did); it may look full and swollen after I'm done, but the measurements don't budge no matter how intense and long my workout was.
Conclusion: hard-on helpers and clamping devices are a MUST for good girth gains after a certain period of manual exercising.
On a side note: I've stopped girth work altogether since I'm not gaining anything, obviously. Right now I'm doing two (or three if I have the time) 30-minute manual stretching sessions every single day, hoping to bust through my length plateu. I will reinstate my girth program once I get my hands on a cable clamp through a Penis Enlargement buddy of mine. It may take a long while before I get it, though (or I may never get it, I don't know yet).