The role of active mobility is to train the body to use the range of motion in the most effective way possible so that the likelihood of maintaining this new range is higher than simply rolling in to the gym at peak hour, squatting heavy, high fiving everyone in the gym and then going home.
The major directions that tend to be lacking in hip mobility are full hip flexion (bringing the knee to the chest), abduction (legs wide apart), external rotation (crossing an ankle over your knee), and even hip extension.
When doing any active mobility, it's best to try to get all the movements down as fast as possible while focusing on getting the movement to come from the hip and not from the lumbar spine.
Focus on keeping the spine tense and the core active while sinking deep into the stretches, hold each for a single breath per rep, and continue on to the next one. Do 2 x 8-12 reps each side.
The total time needed to get the hips singing a happy tune should only be about 15 minutes. If this 15 minutes means the difference between squatting deep into the hole and developing a bigger and better squat, or getting your hips back in a deadlift without having your low back flex to compensate, you'll have a greater chance of pulling big numbers and not getting injured.