You don't tend to have very many months of electives before you need to make some sort of decision. The usual schedule is this (although schools may differ). You do the core rotations in third year. Most schools don't give electives this year. Then 4th year starts in June/July. So that gives you July elective, August elective. ERAS opens in Sepetember, so many will already be applying then. You can do a September elective. Interviews can start as early as October, and run through early February. Not such a good idea to still be "exploring" possible areas of interest at this point (October), and for some specialties, you will want to be doing away rotations by this point. So I'm not so sure you have as much play to explore another area of interest for residency in the "entire fall". You basically have two to three months to explore and decide during 4th year before you need to hone in on a field or fields and line up away rotations and get ERAS in before you start interview season. It's a flaw of med school that they "force" you into the core rotations at the expense of some other very good and popular fields that you won't get any exposure to unless you "burn" one of your very few electives in the start of 4th year. Since you have to figure out what you want to go into, apply, interview, do away rotations, at many programs do "sub-I"s, and take Step 2 during 4th year, it tends to be a fairly congested year until match day. If you have a vacation month you can use to interview or study for step 2, that is often beneficial. Saving it to the end to vacation is well and nice but if that's your biggest goal, your focus is misplaced. Better to have no vacations left at the end of the year and have everything lined up than the other way round. Besides, once you have matched, your electives are pretty much a vacation anyway. The expectations of attendings are low and you are just taking things that interest you.
