My first OB with my first pregnancy informed me that he would be giving me an ultrasound every month until around 30 weeks and then I would receive an ultrasound every two weeks

My current OB, although I make appointments for every month, I had one ultrasound because of bleeding, then they don’t plan to give me another one until 20 weeks but said that around my due date that she will be giving me a couple ultrasounds and our appointments will be more often (around every two weeks)

I am just curious on how often everyone’s doctors give ultrasounds