I initially thought how it would be more strategic if I put my top choices as units that were less demanded, but then I read that they only use the preference sheet once you are selected as a candidate. I know that many of the externs in the past were offered units that they didn't show interest in. I have been offered two externships already and have accepted one, but I will definitely accept Mayo if i like what I am offered. I also have many other applications still being processed. Mayo is too much of a long shot to count on by itself.