Work made with no audience in mind contains nothing that was put there to be seen. Margin drawings happen while your attention is elsewhere, which is exactly why they show what your hand does when it is not being supervised. Nothing in them was chosen to impress, and that is rare in anything made on purpose.

Go find some old notebooks and look at what turns up repeatedly. Those recurring shapes are information about your instincts, and they deserve more attention than the work you were trying hard at.