Automation can bring a mix to life — it can make your mix growl and breathe in time with the music. Automation can be used to change any parameter over time, including things like volume, panning, plug-in parameters, and more. Simple things like increasing the volume in the chorus, bringing the panning on the guitars in a little for the verses, or boosting the bass in the bridge can make a huge impact and provide listeners with enough ear candy to keep them listening for days.
Producers today make as many compositional decisions as entire songwriting teams of yore. How does this affect publishing? Hint: it could use a rethink.