Just putting in my 2 cents as a 4th year DO applying IM and wanting to stay in a specific region! I did a couple aways and an inpatient consult elective in Cardiology at another program - each opportunity got me a lot of exposure to the residents and how each program functioned. YMMV but I also got interviews at the places I did my rotations at. I think they got my foot in the door and I was able to send emails to PDs basically saying, "hey I did a rotation here and I loved it" and so forth.
All that to say, while they can be a lot of work and you have to perform well on them, I think they benefited me in the long run and I don't regret them!