No practice or healthcare system accepts anyone else's records. There is supposedly a way for the patient to release records and have them sent around, but none of the doctors I've asked will accept that sort of nonsense. It's "NIH" for healthcare - if they didn't generate the record, they don't want it.

While in the hospital, the phlebotomists came after me for routine lab work at hospital prices. I declined and then I had a conversation with the nurse about releasing my labs from June to them. On script, she said "Mmm, 4 months is kinda old! We'd rather do our own!" so I filled out the ROI anyway, and curiously nobody offered to draw my blood again.