Four ortho electives is probably pushing it quite a bit. Some may even consider three (some schools even put caps on the #) to be above the upper limit of normal. I've been told by peers/ortho docs that doing too many ortho rotations may make an applicant look too desperate. Most programs want people who are relatively well rounded individuals (aka take a variety of electives fourth year, as I've been told), this may be difficult to do with four months already wrapped up with ortho electives.
Schedule something else during that extra month or two, then plan on taking that as vacation towards the end of the year. I think many would agree that taking vacation time to study for step II is overkill and probably a waste of fun time, most schools offer some type of anatomy or pathology elective that should provide you with more than enough time for step II prep. Plus remember, depending on the number of interviews you pull, you may need to take some vacation time for that --which seems like a better investment than using it for step II to me. That will make the second half of fourth year even more enjoyable and give you time to wrap up logistical things like where to live for residency, drinking beer, etc...
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