There's a lot to this question. > what would be a ballpark estimate to get a reasonably intelligent person with no medical experience up to a "functional" leve

There's a lot to this question. > what would be a ballpark estimate to get a reasonably intelligent person with no medical experience up to a "functional" level? It really depends and I'm speaking out of my comfort zone here. Becoming a doctor takes a really long time because it includes a LOT of background and general medicine knowledge. Doctors know a lot about medicine outside their speciality. Med school is 4 years (2 years of bookwork focus and 2 years of clinical focus) and builds on undergrad significantly. Residency is 3+ years. I'd say the majority of people with STEM backgrounds could have function acceptably as a general doctor with 2 to 5 years of postgrad training. Surgeons are built much more on experience so that's very hard to fast track. In my opinion, the real measure is the ability to handle edge cases/unusual cases. Specialized/limited scope workers, especially those with the direct support of an experienced individual, could pick up tasks much, much more easily as long as an expert is there to take over the challenging cases.