I remember reading somewhere that (disc) brake pads tend to wear more on their leading edge due the "self-energizing" effect (yes, I know, that's a drum brake term) that results as the pads get dragged "back" by the rotor during brake application. If this is true then it might explain the recommendation for putting the squealer tab on the leading edge of the pad.
Now, on the cars I have owned, the pads have always worn fairly evenly if things were working properly so I can't say I have seen this "normal" taper wear pattern myself. That said, I've never owned a vehicle with four pot brakes either where I can sort of see this being an issue if they don't size the leading/trailing pots properly.