I find this very hard to believe, unless you are in an uber-lucrative field (like ortho spine, or something)....but in that case, it's unlikely that you're going to want to work part time, for a lot of reasons.
Part time in most office based fields pays $70K-$90K, roughly. Some offices are very reluctant to hire a part-time physician, because you're only getting part of the coverage, but you still have to pay out almost full malpractice. So, the practice that hires you loses out on the end.
Finally, and most med students do not understand this, but "part time" does NOT mean "25 hours a week." Most full time physician jobs are 60-80 hours a week, so "part time" is frequently actually closer to 40.