Crickets are very aggressive and they tend to cannibalism. If they don't have a place where to hide, they will start to kill and eat each other. Egg carton provides good hiding places so they won't see each other face to face. You must provide them with some sort of place to hide.
the egg cartons provide hiding places.
it also gives them places to stand, so they dont crush each other.
and a veiled (no matter the age) should be supplemented with a calcium without d3 every feeding, a calcium with d3 twice a month,and multivitamin twice a month.