As a mentee, you should be prepared to work hard, and be open to making large changes to the story. These may include (for example) cutting and/or adding scenes, cutting and/or adding subplots, reworking major plot points, rewriting whole chapters, rearranging events, fleshing out characters/POVs and/or removing them. You might end up scrapping thousands of words and writing thousands of new ones from scratch. You're never required to make the changes your mentor suggests, but if you don't agree with their recommended solution to a problem, you should challenge yourself to think of other ways to address the issues they've pointed out. Whether or not you land an agent with your Pitch Wars book, the goal is to come out of the program with a stronger manuscript and better revision skills.