Use only one track a day. If you want to do more in working toward a goal use the Paraliminals. You can use as many as you want, leaving a break between sessions.
With Sonic Access use one meditation a day and make that your focus for the day. Using more than one is no more beneficial and you scatter your energy.
You can choose to alternate them on a daily basis or every 3 days. Just listen to only one Sonic Access meditation a day. You can enjoy the background music as much as you want through the day.
Alex