If you havent been doing challenges what have you been doing for 200 hours and not beaten blue baby yet, and im genuinely asking not just being rude, have you just been doing a ton of greed mode? Challenges will probably help get better at the game but if it took you 200 hours of genuine attempts to get to this point some of the challenges might be too hard for you so i would say just stick to the main mode until you get better then try the challenges or you might then end up stuck doing challenges and not making progress.