Commercial practical
As the others stated, the PTS is the test. On the flight, you will be held responsible for all the maneuvers. The oral will encompass that section of the Commercial PTS. You very well will be asked questions regarding specific instances about when you can charge for services. You may be asked about STCs. My examiner brought in a ferry permit and spent a great deal of time talking about it (I kept my yap shut while he did.). You will be asked about ARROW in great depth. You may be asked about minimum equipment lists and how to deal with inoperative components. You will be asked in depth about your airplane's systems, and likely will have to draw one or more. You will have to plan a VFR cross country, and you will be asked about airspace. Given the times in which we live, it would not surprise me in the least if you are grilled on Prohibited areas, TFRs, and how to obtain the latest NOTAMs about them.
The oral could last anywhere from 1 1/2 to 3 hours. Flight should go no longer than 2.0.
Hope that helps. Good luck with your training.