the mass is one.
i've also heard where its placed matters.
like for cutaways, some prefer as much wood as possible along the edge of the neck at the bass side.
some also like the upper bout to have more wood.
gotta do with having more wood on the bass side so the strings on that side vibrate more etc.

ted nugent guitar, done guess cos hes afraid a deranged dimebag fan would go after him next after he said some stupid stuff about dime after he died.