I'm Brazilian and I don't speak English well, but I'll try.

First of all congratulations on your dedication!

On pages 8 and 9, with the quadrilateral divided into halves simulating perspective, with the ovoids drawn inside, I saw in a Peter Han video that you should draw such ellipses with the inclination of the greater diagonal of the quadrilateral, if they are circles in perspective , so that the most distant ends of the ellipse almost touch the most distant corners of the quadrilateral.

Was I clear?

Inspiring to see the dedication to the exercises!

Makes you want to draw.

Thanks