[jandrese]

It would make sense that military secrets like opting for right hand spirals would not appear in popular publications.

Even the 70/30 split mentioned in the article is telling. If it truly did not matter then you would expect a 50/50 split, so there is a thumb on the scale somewhere. Maybe some early famous castles had them and the feature was replicated in newer castles? But what if the original castles had them for defensive purposes? The newer castles could have been built with defensive features they didn't fully understand.