I agree with this. This is why every note I add must be repeated in spaced repetition style. This way I remember what is in my "mind palace" and keep ideas alive (or explicitly delete them / reduce their repetition period if they are bad). I use Obsidian with the repeat plugin.
I built an entire app around the idea that every note participate sin the spaced repetition queue. For me it has made a lot of difference, as I have managed to internalize (as in put into a practice) a lot of the stuff that I put into my "second brain", for example insights from books I have read, videos I watched or blog posts, etc: