I can have a great memory about some things.
And, when I was a kid, I was noted for having a really good memory.
But, as I've gotten older, my memory seems to have gotten worse.
I can still recall many details with great vividness, but I'll also completely forget about entire happenings.
It's like sometimes my mind has its record button on, and, when it does, it can remember in phenomenal detail.
But, at other times, the record button simply is not on, or what had once been recorded has simply been recorded over.
By comparison, my ISTJ best friend can immediately recall the scores of games from his college team's games for the entire 2004 season.
It boggles my mind how he's able to do it.