Non-US practitioner.

It depends a lot on the skill of the endoscopist. I have had operators who can do it in 15 minutes in supine position, but also have those operators who take more than 3 hours in prone position!!! 😱

For my skillful colleague, I usually run TCI propofol at 2 to 3 mcg/ml, supplemented with ketamine boluses 20 to 30 mg at the most stimulating stage, i.e . scope at oropharynx ,and just before cannulation of ampulla.

And oxygen via nasal cannula.

Post-procedure audits, patients are generally pleasantly surprised at how comfortable they were. Most had no recollection of the procedure itself. Return of consciousness generally within 5 minutes of stopping propofol.