The sketchbook nobody sees is where the brave ideas get practiced.

Courage needs somewhere to rehearse. An idea that would be too strange to publish can be tried out fully in a book nobody will open, and after a few attempts it stops being frightening. By the time it appears in public work it is no longer a risk, because you have already done it four times in private.

Keep one book that is explicitly not for anyone. Put the idea you would be embarrassed by in there this week and do it properly rather than hinting at it. Then check back in a month and see which of them you now feel ready to show.