I've written hundreds of songs. It takes me ten or twenty minutes to write one.
Then it takes me a couple of months (or years!) to rewrite them. Typically they go through about two dozen rewrites. On a few of them, by the time they were done none of the original words or music was still there.
I've never found it hard to write a song. Five in a day isn't unusual for me when I have the time and no distractions. I just need an axe, a pen, and paper. They're always running around my head, and only a few of them make it to the sit-down-and-write-the-damn-thing stage.
I subscribe to the one-in-ten rule: I have to write about ten songs to get one good song. So I only learn them occasionally. There are maybe ten or twenty that I can sing and play all the way through, another batch that I almost know, and another batch that I'll get around to learning eventually.
The folks in the (non-pro) bands I play in like them, so I figure it's worth putting the the time into rewrites, as Hemingway said, "to get the words right."
There are over a hundred my website and maybe fifty or sixty more I want to post when I get around to it. Since I'm not a pro, there's no hurry. Here's the site:
Home
And here's a batch I'm especially fond of:
Oberon O'Blivio and the Outcasts of Samarra
As you can see, I've gotten a little carried away.
Anyhow, here's my song-writing advice, which is worth about as much as the money I've made writing 'em (zip-point-doodly-squat):
Don't think. Write.