Hi Folks... Player owned house, best workbench, protean planks, advanced pulse cores equipped, making the default protean toy boxes (only choice). Each 60 unit run in this double xp period yields 90K xp. The problem is that the number of planks in inventory is not decreasing as expected.
Construction has various effects, that can save your planks - cape, daemonheim scroll (probably not anymore, since it only affects 3+ plank things), measure (dito). Portable workstation and brooch of the gods might also work (possibly not, since other proteans like the meat also aren't affected), but since you're using the one in the POH those are out of the question anyway.