Even as messy as some of the panels we've all seen, can you imagine the number of conductors that would be present in one that was maxed on fill?
Even if you only figure that the wiring areas are sized the same as a 4"x4" raceway, that means that (if you apply the 20% fill rate for gutters and surface metal raceways) there's still 3.2 in/sq (20% of 16 in/sq) for wiring...
Of course, there's supposed to only be 30 current carrying conductors in any one cross section...
