The LC Smith design requires a quality piece of walnut and when an inferior or barely adequate piece, or a poorly seasoned blank was used is when it didn't go the distance.
Inaccurate duplicating was also part of the problem. Their duplicating equipment undoubtedly produced multiple stocks at a time. How many I don't know, but some certainly did come out better than others.
I have reused stocks from obviously abused guns, guns which showed extreme amounts of use and the stocks were still completely sound.
Wood being a natural product every blank is unique; some vastly superior to others.
It needed to be a properly cured quality blank cut from the right part of the tree. The wood above a limb has significantly less lignin than the wood below the limb. The wood below the limb is under stress and has to support the weight of the limb. Compressed wood has higher lignin content which is what makes it stronger. Curl in the grain is a good sign, an indication of material which was grown under compression. Blanks cut from the butt are another example and I personally find stocks with grain from the butt swell to be very attractive.
The stocks which survived without cracking were all dense English walnut and I assume were from well seasoned blanks as no shrinking had occurred. Dense wood may just be less prone to shrinking. If any shrinking has occurred glass bedding will be highly beneficial. If you have the stock off don't miss the opportunity for glassing.