This is unquestionably the most movement-specific supplementary exercise for the sumo deadlift. It helps to improve:
Muscular strength
Muscular hypertrophy
Muscular endurance
Upper back strength
Grip strength
Lat recruitment
Lockout speed/strength
Generally speaking, train it once per week during any given 3-6 week cycle. Sets and reps can range from 8-15+ depending on your individual needs and goals. Obviously low(er) rep ranges lend themselves better to strength development whereas high(er) rep ranges tend to be better for muscular hypertrophy and endurance.
Some of you might have enjoyed the Diary of a Steroid User series as much as I did. It was an interesting, unapologetic, honest portrait of what it's like when an average Joe uses steroids. But however much I enjoyed it, I cringed when I read some of the "pyramid" workouts outlined by the anonymous author