I don't think there is any guideline for # or type of LOR for a PP job. Some want some, some don't. What they are all looking for however is a person that is easy to work with, can adapt to a variety of clinical situations, and can be safe taking care of multiple types of cases.
If you are an a-hole or can only do 1 type of case (i.e. a peds person that freaks out with any adult patient), you are not the kind of person they are looking for. If you are easy to talk to, up for switching shifts if needs arise, and can take care of patients in different settings (OB, outpatient, inpatient, cardiac, peds, etc) you will be a valuable asset to them. Bonus points for convincing them you have some other tie to the area that will keep you their for the long haul. They aren't looking for people to come and go.