Yes, you heard me correct.
Advice over time for the wedges was to file the wear spots to make them smooth. So you can imagine a wedge that has been filed a couple of times being no so good.
So now each wedge will have a different rate of expansion per rotation of the lever. The brakes will now always apply unevenly.
Let me go a step further. Imagine each wedge with several different ramps on them. So as you move them it might move at one rate, then change to a different rate. If each wedge is different, well they might work fine until the shoes wear a bit then you get on a different angle and they move the shoes different.
People do not think much about that, but when you compare NOS to used ones you see some weird stuff. It becomes clear you really really want to have new wedges if you want even braking.
I realize a lot of people will think me nuts for saying this, but then again there are a lot of people with brake problems.