I've been working on a long-term project in my lab where I mostly interact with the head of the project. I talk directly to my PI maybe three times a year so I was thinking about getting a rec from the project head instead of my PI. Is this normal/won't raise any eyebrows? I'm having a little trouble deciding because when I joined this lab my PI specifically said he'd be willing to write a rec when I apply to med school. I know more specific recs normally beat out generic recs, but do med schools have a bias in wanting to see PI recs?