JamesG, that's awesome! I did not know that.
I've only ever worried about shoe placement to the extent that I make sure they are engaging the drum surface without rubbing anything.
Does the "loosen wheel / grab a fistful of brake / tighten wheel" trick work with sealed bearing wheels too? Wouldn't the spacer tube that runs through the middle keep the brake's face plate in pretty much the same place?
Andyh, interesting point. I'm not sure it would work, though.
If you increased the size of the anchor pin, the shoes would be further out at rest, and would extend further each time you pulled the lever. So, wrapping the anchor pin would make your clearances tighter (which is probably good). Also, it would change the angle at which your shoes hit your drum surface (which might be good, or might be bad - I know that it's hard to get the ideal angle).
The reason I do not think that it would really work is that changing anchor pin size is a linear change - whereas changing the size of the cam, or the length of the lever changes how far the brake shoes move each time the brake lever is pulled. This means that you can change it so that pulling your lever the same amount engages your brakes more or less forcefully.
Changing how far your brake shoes sit from the drum wall without changing any of the levers in the system will only change how quickly they engage. If you can pull on your brake lever with all of your might and still not stop your bike, changing the size of the anchor pin won't help (it will just more quickly engage your ineffectual brake).
Full Disclosure: I didn't know what an "anchor pin" was called until you told me (so, thanks!). I know drum brake designs that I've seen, and am always ready to be surprised.