I cant answer specifically for peds, but the advice I gave my interns during residency is this:
to date, no matter how low or high the stakes, whether it be a drivers written test or calculus, I have never gone to any exam without having done some prep work or with the intent to do poorly. Some people may advise you to do this, but i doubt if any of them really didnt do any prep, and if true, im sure they regretted not doing ANY. In any case, Im not about to start giving things away to chance at this stage of my career. It wouldnt be a good reflection of my ability if i did the opposite of what has brought me success in the past.
Even if the stakes are low, trust me, the PD knows how you did, and looking smart in their eyes does give you an advantage.
However, Dont kill yourself to prep
crack open a review book or read a section in an area that maybe you dont feel comfortable with. For IM - high yield for me was always review of the antibodies for rheum. Or Read a section (for IM specificaly mksap) Related to your current rotation to help it stick. Whatever you read will help you on the ITE as well as with your current day to day training
Most importantly, remember that your final board exam is testing the knowledge you have gained over the next three years (or more depending on specialtiy). Dont stop reviewing immediatly after the ite. You have 3 years to prep for boards because you need 3 years! Study your patients, and cases everyday, supplement with qustions all year long and by the time boards roll by, you will be more than ready.
Good luck!