The pleats only tell half of the story. The other half is told when the skirts are lifted, revealing the true fullness. The portraits all indicate a full and flowing skirt with deep folds reaching the floor. The fullness is indicated not only in the way it hangs, but also when the skirt is lifted there are abundant folds in the woman’s hands and the unlifted skirt remains fully pleated. Along these lines, when the gown is lifted to expose the colorful petticoat, it is worth noting that it is likewise full and flowing as opposed to a farthingale or other hooped petticoat.
An excellent source, and the closest extant we have, is the gown of Mary of Hapsburg. While the front is flat, the back does show floor length folds created by a circle skirt that is gathered on the sides and back. The construction of the gown is interesting as it gives a similar effect as those in the paintings without as much fabric consumption as various pleating options would require.
The idea of a circular skirt is not limited to the gown of Mary of Hapsburg. In a 16th century German Pattern Book: the Leonfeldner Schnittbuch c. 1590, on pages 36 &37 are sketches of what appears to be a woman’s gown. The bodice is clearly defined and appears to have the skirt at least partially attached, whether it is cut out this way or sewn together is unknown. Of particular interest is how the skirt at the waist section extends beyond. Could this be to allow for pleating of some sort or just plain gathers? Unfortunately, the circular skirt appears to be the only similarity so it is uncertain if the pattern, dated 70 years after the extant gown, is of any relation.
In examining the pattern, it can be noted how the skirt extends straight out past either side of the bodice before starting the slant downward for the sides of the skirt. Even with pleating this strait section into the waist line, the skirt would not fall as represented in the paintings. Instead the fabric would be concentrated at the quartered points and remain smooth across the main part of the waist where it attached to the bodice. This effect is discussed further in the Burgundian blog. However, if the bodice was detached and the fabric carefully and evenly pleated, this design layout may have merit for the early 16th century German Saxon gown. It might also work well for some of the lower class gowns where paintings show pleats only at the sides rather than all the way around, but still allow for some fullness to the skirts.