Madara's best feats are regenerating a whole lower body and recuperating from the mess that Gai made of his upper body. Kaguya's is regenerating an arm.
From Kaguya's inexperience of her prowess, it would appear she takes time to regenerate lost limbs; example being her arm cut off by Naruto, and she needed a full chapter to regenerate it. Madara regenerated half of his body at such acceleration, even before absorbing the Shinju.