Deconstructing serifs on broad-nib based typefaces


I'm breaking down typefaces to try understand their construction — brush strokes, direction, angle etc (manual Kalliculator you could say). Currently I'm looking at broad-nib based typefaces, and I'm hoping someone could shed some light on their design and construction with regards to serifs.

This is what I think it may be: the white lines being the 'brush', starting at 30 degrees
and arrows the direction it travels — are these serifs shapes constructed without regard to the brush or do they follow it some how?

Another example is Dolly, where the serif is asymmetric and I've no idea how that's drawn,