That was stated before, I was referring to the enrichment paths, especially the nova modes that accelerate the remnant to high speeds and it accrues material by flying through nebulae or God smacks an iron planet such as mercury and the iron migrates to the core and the cooling is accelerated ...
Supposing that all the paths to an iron rich core white dwarf are factual and this remanent would cool much faster, how long would it take to cool to obtain a terra firma crust