There's a story that Bob Dylan met Leonard Cohen and they talked about songwriting. Bob told Leonard that such and such a song had taken five days (or whatever) to write. Cohen replied that his song, whatever it was, had taken five months. Later, he confessed that he had lied. It had taken five years.
Noddy Holder used to say if a song took more than five minutes to write Slade would give up and start another one.
I made up the time periods because I couldn't remember them and I didn't want to look it up because, you know, spontaneity was the whole point of the post. This picture gets finished eventually and looks like this.