Real exams only in France : it was depending on the doctors and if they were young or middle age or old and if it was on the past or recently.
Recently it is obvious that the most frequent position required by a doctor is lying on the side with knees bent up to the chest, but some years ago I have been told by a male doctor pretty old to sit on a table on all fours on elbows and knees, he had told me that it was for him the easier position but if I disagreed I could be on my back or on my side, I told him that I had no objection and I took the position on all fours and it is the best in my opinion, you do not see the face of the doctor, you feel only his fingers when they are inserted in your asshole and after he had spread your butts with the other hand.
An old woman doctor between 50 and 60 age had also required this position on all fours at an annual check up and she had instructed me to spread myself my butts widely. She did first a visual inspection of the anal area with a few comments about the fact that I had very few hairs on the sides of my butts, and then she put some vaseline and she inserted her fingers.
At that time I was about 35 age and it was the first time that she did a DRE at my annual physical examination.
She was what we called in France a doctor of "the old school " because she required to the male patients to be naked for all the time of the examination which was not required by younger doctors.
I was not surprised because I had been instructed to take that position many years before as a young man at physical examinations for the military service, I have had three physicals between the age of 18 and 21 before being declared fit and each time, I have had a DRE with the position on all fours required by the military doctor and the same after induction at a regular physical examination, the military doctors did not give you the choice, it was on all fours by their decision.
But now for medical reasons, like check of prostate, it is rather on lying on the side and a knee on my chest.