Bottom line for both the shackle bolt and the proofide, like everyone else has said, do this when necessary. If you're not sure it's necessary, it's not necessary. If it is necessary, go for it, but don't overdo it.


TLDR: When a saddle leaves the factory, the leather is under tension, which comes from the frame being a little bit "too small." The frame is a strong springy steel-- it will flex a fair amount but will not ("should not") take a permanent bend unless it takes a serious hit. That tension is often all the saddle will need, but if you ever have to ride the saddle while the leather is soaking wet, it will probably stretch permanently, and the tension will be lost. If the nut is loose enough that you can tighten it without a wrench, go for it. If the bolt is actually loose and rattling around, you can definitely take a wrench to it and tighten it until it's not rattling anymore.

As for proofide, if you ever have to ride the saddle in the rain, with wet pants, you will probably notice the surface of the leather looking dull and porous after it dries. That's when Proofide is necessary. But go easy....