Our minds are not camcorders, and our recall (even in the healthiest of people) isn’t always as reliable as a lot of people think. As time passes, details, or even sometimes entire episodes, can be forgotten. A simple example I’ve used before in my writing online is the mundane one of forgetting where you left your keys.
I’ve always found it interesting that the brain sometimes even straight up FABRICATES “memories” and rarely do most people question their authenticity. I wrote before once on a blog about a “memory” I used to swear was real, of me going to a red headed woman’s funeral when I was very young.
I later found out that this “memory” wasn’t true.
My advice, while the brain is a great thing, it’s important to realize it’s limits & take those into account. Seek out secondary corroboration of memories whenever possible and as necessary.