There are many theories like this, but here’s mine:
If you’ve ever heard me talk about Song A Day, you’ve probably heard me mention this. Seventy percent of the songs you’ll write will be mediocre. Twenty percent will suck. But ten percent will be amazing.
I first started thinking about this way back in college. I had two revelations almost simultaneously: First, my friend Will and I had stayed up late one night recording forty songs, each 40 seconds long, into a tape recorded. I listened to the tape all through over the next few days, and while much of it was just stupid fun, there were a few out of the 40 that turned into songs that became part of my repertoire for years to come. Second, I thought back to every CD I had ever purchased (a big deal back then when albums cost $20 a pop) and how there were almost always only a few good songs on every record: The Hits. Everything else tended to suck.
The trick to making an album that doesn’t have tons of filler is writing lots of songs, then sifting through them to find the 10% that don’t suck. According to Quincy Jones, Michael Jackson went through 800 songs to get the 9 that appeared on Thriller (that’s almost certainly exaggerated, but the point is clear). There are countless stories like this behind classic albums.
The more songs you write, the more good songs you’ll write.
It’s not “quantity or quality”. It’s: “quantity breeds quality”.