Just checked my 2 personal bows, .550" and .650"
One has a lot of phenolic in it and the other has 2 pcs of glass and 3 pcs of wood in it...
Like Mike said .750" is safe, and less flex(which slows the bow)
That spot to left of arrow in top pic is the weak point, corner of sight window to thumbrest.
Radiusing like Mike said helps...