Howdy, Pards,
Let me respectfully, but firmly disagree with the use of Neat's Foot Oil on leather! NFO was intended to prevent horses' and cattle's hooves from cracking. As such, since it it used primarily on living tissue (similar to your fingernails), it doesn't matter if the hoof softens too much, since the hard materials are replaced by more tissue.
NOT so on tanned leather. Neat's Foot Oil will eventually rot the fibers of the leather, and make it fall apart!
I personally have use Lexol Leather Conditioner, IN MODERATION, on all my topgrain cowhide products (holsters, belts, accessories) since 1975, with excellent results. Even in a dry climate a limited application (spray or wipe on) of Lexol Leather Conditioner applied once a year will usually do the trick. Of course, you may want to apply the stuff when the leather has been thoroughly wet, such as in a rain or snow storm, AFTER the leather has been dried AT ROOM TEMPERATURE.
OLD leather that has dried to the point where it is cracking or the surface flaking is probably irrecoverable!
It too bad, but if it gets that far, it is probably too late!
Hope this is of some interest and help!