you obviously won't need a princess 8n every battles , but then again , you don't even need witches in every battle either....or extra hp on your units for that matter. For people that will have other witches (like belinda that can increase attack for all witches) or even cloris with ranged assasination , they will probably use those over adele , since witches are used more for their utility then damage (in belinda's case , her big big range , and i cloris's case , her chance to insta kill stuff - which is better in both cases then adele's utility in general) , then deploying a witch to give units 10% extra hp. I mean , adele is even more situational then sybilla in that regards