Can scribal hands be correlated to imagery? Let's look at faces!

[ReneZ]

The round-faced early Zodiac figures and the single root face in Pharma are very well executed and of good quality. The early Zodiac nymphs come in a variety of dynamic poses while the later ones are more rigid and often poorly drawn. Why is there such a decline throughout the zodiac?

My guess is that this is due to a general decline in the quality of the zodiac illustrations.
This can be observed in several different aspects. I had never looked to closely at the nymphs' faces,
except that one time when I needed a particularly ugly one for a talk. I found it towards the end.

The first sign uses a wider piece of parchment, such that the full height of the page could be used to fit in a large circle. This was not done for the next two signs, where much smaller circles were used. But these were split in two pieces each. Possibly, this was just for quality reasons.
However, this was dropped, and for the remainder the full circles were squeezed in the smaller width.

Painting is only used in the beginning.

Equally spreading out the nymphs gets worse towards the end.

Is this a sign of loss of interest? Increased haste? 

The circular designs are all from hand 4, and these may have been the last ones. 
(Hard to say if the Rosettes page was done before or after).