I'm under the anecdotal and subjective impression that I can do a "brain dump" describing a recently-experienced physical event. But it's a one-shot exercise. Close to read-once recall. The archived magnetic 9-track tape that when read becomes a take-up reel of backing and a pile of rust. The memories feel like they're degrading as recalled, like beach sand eroding under foot, and becoming "synthetic", made up. The dump is extremely sparse and patchy. Like a limits-of-perception vision experiment: "I have moderate confidence that I saw a flash towards upper left". Not "I went through the door and down the hall" but "low-confidence of a push with right shoulder, medium-confidence passing a paper curled out from the wall at waist height, and ... that's all I've got". But what shape curl? Where in the hall? You've whatever detail was available around the moment you recalled it, because moments later extra information recalled start tasting different, speculative fill-in-the-blanks untrustworthy.