The quads are the body's heavy artillery. They are the biggest single muscle group in the body and they are key to powering everything, from jumps, runs, sprints and kicks to punches and skips. Quads are the body's mobility engine and training them should be a primary aim in your fitness horizon. Keep in mind that it wasn't for nothing that the Spartans, the ancient world's most fearsome warriors, spent an enormous amount of time training their quads as they went about all their life, in their mountainous homeland. This makes the Pistol Squats Prep workout one you should aspire to. By all means "attempt when ready". Test yourself and once you conquer it, keep coming back for more.
Extra Credit: 1 minute rest between sets.