No, physical destruction of the sigil isn't necessary. I've kept a 'grab bag' of sigilized intents for further use. (It is a rather subjective view) The act of forgetting is the key component here. To me, decades pass like oily water, it is easy to forget past sigils. Though I'd imagine that someone with eidetic memory should destroy the sigil, thereby sundering the concious link. When in doubt, destroy it!
I apologize for the thread moving off topic. It was my fault.
You appear to have thought this through. How does your approach deal with the problem? It will, ultimately, be your methods that you use. Each individual must adapt a method that suits themselves when it comes to 'tricking' the concious mind. Right? (IMG:
style_emoticons/default/rolleyes.gif) Of course all of this is my humble opinion.