Why is "heavy braking" recommended in an aircraft with carbon fiber brakes in order to prevent brake wear? That seems backwards!
I know nothing about this topic but it's quite an interesting one so I did some Googling and found a detailed Airbus document called "Proper Operation of Carbon Brakes". It includes the following information:


  All brake manufacturers highlight the fact that carbon wear is heavily
  affected by brake temperature


This is completely different from steel brakes:


  ...energy is theoretically not the primary parameter for carbon wear,
  whereas it is the  most important one for steel brakes.


The document goes on to say this:


  Generally speaking, to increase carbon brake life, brakes should
  either be operated cold or hot but not at intermediate warm
  temperatures


And this:


  All recommended braking techniques should aim at reducing the number
  of brake applications and optimizing the carbon brake temperature


The specific temperatures mentioned in the document are different for different manufacturers, but generally the intermediate range to avoid seems to be roughly 100-300C. That would explain why 'heavy' braking might be recommended: it's better to use one single brake action that generates more heat and gets into the higher temperatures than to brake multiple times more lightly. Nevertheless, the document also says that overheating is still unsafe and the use of max autobrake is not recommended.

I found a related discussion of exactly this question elsewhere that goes into the physical explanation (although it doesn't quote any sources): at lower temperatures, the carbon becomes a powder which abrades the brake pads, lowering its life; as the temperature rises, the carbon starts behaving like a fluid so the wear is greatly reduced. Most discussions of carbon brakes that I found say that their physical properties and behavior are well documented, but not well understood.