Failing to match among US grads is far more common among applicants applying for highly competitive specialties (derm, ENT, ortho, neurosurgery, radiology, etc) and is often due to an applicant receiving too few interviews/ranking too few programs or just not being competitive enough for the desired field. Outside of these specialties, failing to match is pretty uncommon.
When picking programs, we're generally advised to aim high and apply to a mix of "safety" programs, programs we'll be competitive at and "reach" programs. If you're a decent applicant and are not too limited by geography, this should yield a fair number of interviews, enough to ensure that you won't have to scramble.
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