All this is "picking the fly s**t out of the pepper."

Leather saddles don't really need to be conditioned until they need to be conditioned. That can be out there a decade or more, depending upon local weather and riding environment. All this stuff is good to use - up to a point of excess. Just don't over do it, and you won't go wrong.

About waterproofing: Why waterproof a saddle that earns it's fame from the fact that it is supposed to wick away moisture from the rider, into itself, then evaporate it out later? Some added water-resistance makes sense, but waterproofing is somewhat counterintuitive.

The amount of Proofide that goes onto a saddle is about the same as you would use to shine your shoes. It has minimal effect upon the leather if used according to Brooks' instructions.

Cold forming with water is a millenia old method of shaping thick hide blanks so they retain their form. The Romans and others did this to form the leather breastplate cuirass armor we see on classic statues of Julius Ceasar. I don't know if Brooks uses this method, but it wouldn't surprise me at all. Getting a saddle soaked will not cause it to fail early. Riding a soaked saddle may very well accomplish that.