I've had a somewhat different experience with the office supply rubber cement- It's way too thick and even if the inner tube is scuffed up plenty, the patches just don't stick as well as when using the special "vulcanizing" cement in the little patch-kit tubes. YMMV. I think it's the solvent mix used in the patch kits versus the solvent in the office supply stuff.

I put vulcanizing in quotes, because vulcanizing is a heating process (Vulcan being the god of fire). I don't recall heating any of my bike patches. I haven't used heating since using the patches you light with a match when patching an tractor inner tube.