We don't have "Sr Drs", the new Drs are residents until they become full fledged Drs.
We have many specialists in all fields.
When my bleeding problem became a concern, I called my GYN and made an appointment. On that initial visit, November 26th, she did the endo biopsy, psp test and bloodwork. She gave me a requisition to get an ultrasound. Nov 27th was Thanksgiving so offices closed. I had my ultrasound Friday, Nov 28th. All results the following Wednesday.