Assurance: Medicine precludes the need to roll altogether, and honestly is a near-mandatory pick for the tabletime it saves. You might save a little in-universe time by manually rolling with a high modifier, but unless your campaign is running at breakneck pacing, the difference isn't worth the real time spent. Recall Knowledge checks with medicine are the only reason I'd want to manually roll, and Anatomy Lore covers a huge swathe of that subject anyway.

All that to say, ehhhh its probably fine to brew up that Medicine->Anatomy Lore feat. I wouldnt reccomend doing something similar for any other skills though.