Testing again and again!?

I'm new to this. I have never had to count days pays ovulation in order to test (I'm testing in the am) I am waiting for my BFP. But once I get that I will be calling my doctor. Can someone please explain to me the woman that get the BFP just still continue to test everyday and sometimes twice a day?? I don't get it. I am not talking about women who are having issues getting pregant but the ones that just keeping testing. Help me understand this.