I tend to use the thick one for that and than only need one layer with good results.
Have tried the thin one and needed some 6 layers and struggled.

I have always had good results using one layer of Ultra Solvy made by Sulky which I buy from Joann's.

It depends on what you have bought - I use two layers of the mesh (material looking) WSS - one grain flowing in each direction. (If you have the thin plastic WSS - that is a topping - more for on top of a design - so that the embroidery threads don't disappear in the material.)

sometimes I like to double stitch it, so I use 2 layers like shirlene said, the hardest thing is to make sure it does not shift while stitching, so make sure it is hooped tight. if it shifts even a little the designs do not hold up all the time. I have done some that my WSS shifted and the outline of the design just hung in midair, total waste of thread and WSS and time LOL I guess sometimes we all learn things the hard way.

Thank you to everyone!

you will know how many you need
when you have to much holes lay a new wws over that
so that you can emb again
thats what i do every time
hugs Sonja