The term as applied to warships, was bigger and beefier all around. Sort of what they did with their wrench. Working on old machinery, pre-1930 the bolt heads and nuts were usually much thicker than today. So I can see their reason for this style. Also have some adjustable 12 inchers, Crescent and others that the jaws are significantly thicker than today. Have you noticed any Kraeuter and others with very thin jaws, stamped Checknut?