Doctors almost never act with full information. Doctors don't even want full information. It wastes their time. If you come to a new doctor they will make you fill out a stack of forms where you inaccurately self-report your medical history and then they will toss that in the rubbish bin. If you so much as dare to suggest that a doctor should transfer your old medical records from one place to another, they will vehemently object and question why you would want to do such a thing. In fact it is far easier to sign a release of medical records and authorize their release, than it is to cajole any given Records Department into accepting the transfer of records in any format, much less a machine-readable format that would be useful.
I believe it is a liability for doctors to know a true medical history, and anything not already being treated can be ignored and re-diagnosed later, which of course is an ideal situation for the insurance and the new provider, because you can charge all over again for those diagnostics.
Case in point, I had two EKGs performed on me, one in urgent care and one in the hospital. It was not too long before I was going in for surgery, and a prerequisite was a "12-lead EKG" readout, so naturally the hospital tried to force me to undergo a new one at enormous cost and inconvenience, and I balked, because I already had two perfectly good readouts in hand. They eventually relented, but it was incredibly difficult for them to admit that the test results were valid and acceptable, and this is all part of the scam, to charge as many times as possible for anything that wasn't performed here and now by us.
Likewise with psychiatry and therapists; I've been through multiple clinics and dozens of counselors, and of course each one produces a mountain of case notes. So I always offer and suggest that I sign a release and have all the prior case notes transferred over so that they get to know me better. The answer is always "no". They want to know nothing beyond what is in the intake forms, that they will spend 5 minutes reading. Then we will start my therapy over from Square One with a stranger and I get to recount all my feelings and life experiences over and over and over again, on my dime.
Nevertheless, it is still of the utmost importance that you continually sign authorizations for release and that you requisition all available records from all your providers. Authorize all providers to release information to your friends and family. They will hang up the phone if there is no release on file. Renew those authorizations on time, every time; your provider will not remind you. Release all records to yourself on a regular basis, especially after a hospitalization or major incident. You will want good records, just for your own examination, and also if there is ever a dispute or litigation about something, your attorney will appreciate those records too.