This "overengineering" can be quite apparent in wooden necks too, and the difference can be quite substantial. I've had 4 and 5 string versions of several of my basses, and despite sharing the exact same specs in terms of woods, electronics and construction, they always sounded different: the 5-strings have always sounded tighter and slightly harsher, without the warmth that the 4-strings exhibited. The only difference was in the neck, which was always more rigid (and just simply contained more wood) than the 4-string counterparts.
My graphite necks are actually the exception here, because the necks on my Status S2 Classic 4 and 5 are more or less "hollow" shells.
It was most apparent in my Ibanez ATK's, of which I've had two ATK300 4-strings and one ATK305 5-string (and at one point I've had a second 305 at home that was passing through, so I could compare them). The 5-string necks were much more rigid and those 5-strings lacked the beef of the 4-strings and had more brittle top end than the 4-strings despite being 100% identical in every other way.