Assuming a normal ball position (middle of stance short irons, progressively further forward through the bag to just inside instep with driver), I believe that at address the butt of the club should point anywhere from the zipper to the inside portion of the left thigh. That'll give most people a few inches of leeway. No such thing as an absolute fundamental in golf - so to say the hands must be positioned in some precise manner at address goes against what you will see week in week out on the professional tours. It is more a range of workable possibilities and the optimum position for any individual will depend on the nature of their swing. What I see is that rotary style players have the butt pointing more towards the zipper, arm swingers more towards inside of left thigh.
Personally, I'm an arm swinger and position my hands so butt of club points at inside of my left thigh. With my short irons there's a noticeable forward shaft lean at address, with my driver the shaft is leaning a tiny amount back. Might vary a little when I'm creating different shots. Overall it works great for me.
