the half-decay periods of blog ideas

Once a while, an itch to write creeps up -- be it inspired by reading, stimulated by travel, or stung by actual or imaginary mosquitoes. Some ended up being a post on an infrequent blog, like this one; some continued to itch for sometime but ended up nowhere, like most.

I wonder how long the itches would last with the normal wear-and-tear of life. Is there a half-decay period for the urge to express in writing? The geek in me wanted to launch into a three-sectioned discussion about the nature of motivation, and what the internal fading and the external grinding can do to writing itches, while the blogger in me said that this is utterly unnecessary. The commonsense in me hopes that the happy thoughts and positive revelations would fade slowly, while frustrations, anger and disappointment would decay fast -- since they are supposed to just stay as itches, albeit being no less true to ourselves than any of the better feelings.

I had thought the revived blog would focus on external subjects such as books, films, gadgets, and maybe food and travel to come. This is certainly a diversion. This said, I am hoping to salvage and revive some of the nicer itches from over a month ago, and one thing about exponential decay is that it will never be exactly zero :)