That does sound rather concerning if that's the case!
As a medical student about to sit my final exams, I have shadowed hundreds of doctors of different grades and specialties in many different hospitals and family practices, and I don't recall ever seeing a doctor not review the notes before seeing a patient. Often here in the UK at least there is a large amount of time pressure and it would certainly be desirable to have more time to review further back, in more detail, etc. but given in general practice there is a 10 minute slot per patient, there are systemic limits on this (that would be nice to address).
On the other side, trying to figure out what is going on with patients is much more complex than catching up on notes and trying to get a "delta" update from them about what has changed in the shortest space of time/words as possible. The number of times I have taken a history from a patient and then less than half an hour later observed them add hugely important extra details that were omitted previously is pretty large. Often, it is far more helpful and illuminating to ask a patient to tell you what has been going on in their own words, even if you think you have read it all in the notes. I have often seen more senior clinicians pick up subtle clues that were missed by more junior clinicians, or ask a pertinent question that was not asked before.
And finally, on a more pragmatic basis, doctors take a lot of risk on board whenever they treat a patient. Patient's get tired of people asking them if they have any allergies for example, but when it's your name on the prescription, and your ability to sleep and your license on the line, you may well decide to ask the patient again rather than rely on what some previous clinician in some previous setting has written down on the patient's file. In a similar vein, a lot of practice is not black and white. If a junior with limited experience writes that a particular clinical sign is positive in the notes, you may well want to repeat that examination to re-assure yourself before you allow it to guide your treatment.
None of this is excusing unpreparedness or poor practice, but hopefully shines a little light on some reasons why it seems like there is so much needless repetition.