This is a great superset for the posterior chain: the hamstrings, glutes, and lower back. Without resting between exercises, perform the Romanian deadlift, a sled push and then a sumo deadlift.
Elevate the toes on the Romanian deadlift to better target the hamstrings.
Pushing the sled with a wider leg stance better targets the glutes.
For the sumo deadlift, avoid raising the hips too fast when you lift off the floor. As soon as you pass the knees, snap those hips forward by squeezing the glutes.
Admit it. A lot of times you plan your workouts around your major muscle groups and just "throw in" a few sets at the end for your ancillary muscles – calves, abs, and forearms.