It is different in Emergency Medicine. One from a good ER program along with the other 2 from major specialities, like medicine, surgery, or pediatrics. So for ER the ideal combination would be a letter from a medicine attending, a surgery attending, and an attending out one of the best Emergency Medicine residency programs listed below. What you do in the 4 th year isn't important, assuming you take care of the other things. Nobody will care if you do an MICU rotation or not.
Applications Apply to a lot.
Thirty is a reasonable number. Have a who range of quality. That is, a place that will certainly, or almost certainly, take you to be at the bottom of the list. Scrambling is not a good idea. Don't plan on it as a fall back.