I believe those "layers" are just pieces of cloth within the epoxy resin. Fiberglass also has layers of cloth in it. That helps add strength to the material. I actually like seeing the layers as I believe it adds character like grain in a wood.
I did some testing with phenolic...getting a 1/4" thick piece that was only a 1/2" wide but about 18 inches long. I grabbed both ends of it and put my foot in the center and proceeded to pull on it to flex it excessively. I bent it over 1/4 of a circle before it broke...but I was able to break it. The amount of force I put on it was great enough that it would have broke ANY and ALL pieces of wood I have ever done the same with. I inspected the ends where the break was and indeed it did show some separation of layers...but again the force I put on this would have broke any type of wood anyway. In fact, the wood would have broken much earlier. I don't know of any wood that is actually harder cut or grind or that is more durable. Phenolic is very tough. It will ruin a bandsaw blade or a table saw blade pretty quickly...but that is just a cost I have to accept as that is also why I use it.
That said, I decided that every bow I make is going to have 1/4" of phenolic running through the sight window to reinforce the cut out of the sight window...either by using one piece that is 1/4" thick OR by using 2 pieces that are 1/8" thick that are separated with a wood lamination stripe in between them.
However, I do not bend the phenolic when I use it. I use it for strength and when you bend it one creates internal stresses not only in the phenolic, but also by flexing the material when used to create curvature laminates the glue joints in such joints are under internal shear forces that simply put are avoidable. If one uses 1/16" laminates, this is a minor issue because thinner materials are more easily flexed and experience less tension/compression forces within them, therefore they create less shear forces in adjoining glue joints. However, thicker materials offer more strength, but should be used in their natural straight condition.
Now...all that said, I do NOT use it in my fade outs. My reasoning for this is BECAUSE it is tough. I personally don't want my natural limb cores to be working against such a material. I keep my phenolic limited to non-working portions of the riser for this reason.
Is this a "con?" Probably not, as a good fade out of any material will be thin and taper smoothly out to nothing...but when in doubt I try to side on the side of caution.
This is also the SAME REASON I do not use "I" beam laminates in my riser that are parallel to the direction of drawing/shooting the bow. I like my grain in my wood to be parallel (quarter sawn) for strength, but my laminates are all perpendicular to this. This is because different materials have different "flex" strengths (modes of elasticity). I want to prevent pressure points...and to do that I need the fade out to function in unison with forces distributed evenly.
(Note: If I need to photograph any of the stuff in this post, let me know...be it the broken phenolic, how I believe phenolic should be used, how I believe it should not be used, or what I mean by "I" beam laminates to illustrate why I don't like such laminates.)
Phenolic is GREAT when it is used properly, but I think there is a right way to use it and a wrong way to use it.