Soaking is probably to blame for some of this, Soaking doesn't help with getting 1 piece sheds, nearly as well as Just give him 1-2 mist's a day.
My room humidty is 55-65 depending on the day in Summer here. And on coco husk they all shed 1 piece, dampening it before shed. My smaller guys who are on paper till 600+grams, Get misted one time at night and have all had perfect sheds.