Is there a Chinese equivalent of the German "Mut zur Lücke"?
google told me "Mut zur Lücke" means "dare to venture into the unknown", and I can't find a Chinese phrase that have the same meaning xD. But there is a expression, 碰运气, which means to "push your luck". So in your example about the exam, you can say 碰一碰运气吧，这部分我不复习了(Let me push my luck and skip this part).

P.S. In Chinese, 人品 means moral qualities. Chinese people sort of believe in karma, where people with good qualities(人品好) will do good deeds, good deeds will be rewarded with good luck. So you can replace 碰运气 with 拼人品(the collocation can't be changed, 碰人品 and 拼运气 are not proper expressions). But this expression "拼人品" is informal and is only used among young people.