As someone finishing week 1 of my consult rotation (List fluctuates between 22-26 patients), working from 5 am to 7 pm.... AND I happen to have a black weekend this weekend.
Dude. Enjoy your damn 3rd year. You'll learn on the job.
As much as these hours blow... when you take a perfect story to the cath lab with negative trops and no EKG changes and everyone is annoyed with you, and it's a 100% LAD; It's all worth it
If you love cardiology, you'll absorb and learn through osmosis like you did in residency.
Be a good clinician, do whats best for the patient, and yes, be a good internist; half the time your consults are non-cardiac issues with cardiac side effects and so you have to educate them on what's going on from the medicine side of things. Remember, in fellowship, you're a board certified Hospitalist (assuming you pass ABIM)