I used to listen to music in my office every day and could not stand to work in silence. Somewhere in the last few years I would find myself working in pure silence accidentally as I would turn my music off to take a call and then forget to turn it back on. Once I realized the power behind the singular focus I decided to stay the course. I no longer play music while working and while that would seeminly be a pro I have inevitably found the cons as well. My work is more intense, likely because of the singular focus. I have too much room to think, contemplate, and amplify without the background of music to calm my inner voice. I like your discipline of changing it up every few days. It removes an all or nothing approach allowing for some variety.