Im blessed to do both. I agree writtin scripts or lyrics is the best way to make some tight songs. Speaking of Jay-Z. This cat never writes. I seen a 45min video documentary about him makin his last album. This video showed him in different studios lacin tracks. This cat doesnt write. He will listen to the beat, go in the booth and just spit. He even memorizes the stuff he said as if his brain is like a huuge memory computer.
I go in different ways in makin a song. One way would be me in the zone and can write a hit song in an hour or less. Another way I do when I have writers block, I would listen to the beat, and freesytle while listening to it. Any tight ideas I get while freestylin, Id jot it down.