How long each session?

Danyne • Married July 2017. 💖👶🏻 Adelaide Iris- 7/30/19 🤰🏻due Dec 21

My baby is 1 week old today.

I just decided I exclusively pump for sanity reasons... but my question is how long should each pumping session be?

In the hospital, when I was trying to breastfeed and pump, they told me to pump for 15 minutes after each nursing session. But now that I’m not nursing, should I continue just 15 minutes every 3 hours? Or should the length of the session increase?