My n=2.5
I was part of the applicant review/interview committee at my residency for the past 3 years, and am currently doing the same for both my fellowship and it’s associated residency program. FWIW, my residency program was previously very DO friendly but by the time I started as an intern it was lukewarm at best, however interviewed(s) a fair number of DO applicants every year. That an applicant was a DO was never explicitly factored into ratings or rankings for any of the aspects in which I was involved (unless an interviewer did so implicitly). So, basically everything except making the program match list, which was solely up to the PD at the end of the day; but I did see it prior to the match every year and it never seemed to depart from applicant/interview discussions prior to that point to suggest a clear, explicit bias against DOs. For the applications I reviewed (both DO and MD) I never really looked at shelf scores as a specific data point but rather the MSPE as a whole, and if anything paid much closer attention to preceptor comments. MSPEs are basically like trying to read tea leaves and not all schools include student shelf scores in them.
Same approach in looking at residency applications where I’m a fellow, though this is my first year here so Idk if others will do differently when it comes to rating and ranking applicants but I highly doubt it. For fellowship applicants the MSPE (and thus shelf scores by association) are basically a formality.