Like Vixen, my experience varies. I always have creative muse undercurrents at work, 'on the back burner' at least. My songs now, develop over time. Everytime I play at home, and often when I perform, I 'play with' musical ideas I am working on; tunes, progressions, etc. Ofetn times, lyrics are easier for me than the deciding how the stories will go! That is, it easier for me to find words when I am very clear on what I want to say, and how I want to develop the story of the song. I used to write a song in a sitting or two. Now I write several per year, none of which I completed in a single sitting.

How long do they last? None of my songs from 20 years ago remain in my repertoire ... but bits and pieces of them do. I steal from myself. Sometimes I take ideas I like from old songs and roll them into new ones. The good news is, though, I suspect my new ones I will carry for as long as I sing.