Totally agree, I know someone who applied and interviewed at only to 2 programs and matched and those that went on 15 and did not. No magic number, somewhere btw 8-12 is a good number though. Also agree it depends on how many you applied to as far as your chances. If you applied to under 10 programs and got 3 interviews, that isn't that bad and is better in my opinion than someone that applied to all 100+ and got 10 offers.