While I agree with the spirit of your argument, I don't think it pans out. It's almost impossible to really know what specialty you would enjoy day to day for the rest of your life. Electives aren't adequate enough to paint that picture for you. And even if they were, no body has a single field of interest for very long. So an extra 3 years, or 5 years for that will almost certainly NOT guarantee that you're doing something that you love. Otherwise the satisfaction rates in medicine wouldn't be so low. I definetely get where you're coming from, I just don't think it seems to work out that way.