Pumping too long?

BLPL101

I EP and normally pump around 20 minutes every 2.5-3 hours and I get about 6 ounces total. Recently after 20 minutes my right breast still feels hard so I kept pumping. My left breast was empty at 20 minutes. I pumped the right breast for 45 minutes this morning and milk was still spraying out! I got 5 ounces in that time from the right one. I know you aren't supposed to pump that long so should I pump until it's empty or stop around 20 minutes??