Young Ninja Group (ages 3-5)

I have reached the point in calculus where every new lesson seems connected to something I learned weeks ago. If I forget one step, the whole problem falls apart. While searching for help, I saw take my Calculus Exam and realized what I really need is stronger practice with the basics. I am thinking about going back through earlier problems before touching the newest material. Has anyone done this close to an exam? Did reviewing the foundations make the harder questions easier?