Wouldn't use of the leather also influence what it's cared for with? There's products I use on shoes that don't touch other leather goods and vice versa. And I'm dealing with a fairly narrow range of men's goods (e.g. shoes, briefcase, belts). Add in stuff like saddle bags and you might have several different products for the 'same' leather.
Well, yes, but I wouldn't put any petroleum based oil or grease on any leather.