Comment by zowie_vd

The paintings in the article are mostly 15th century, which is only early renaissance. The understanding of light in painting was still somewhat limited in those times. I think in the case of almost all of these paintings it's more a matter of technical competence rather than artistic intention (exceptions include "Madonna and Child Enthroned with Saints" where I reckon the shadow ends early for compositional reasons). It's interesting to look at this to get a sense of the various ways people can get something wrong before someone gets it right.