The Deadlift
Using the Competition Deadlift to develop strength works but is contra-indicated.
While it increases strength, the downside is with each repetition, your technique is altered due to muscle fatigue.
Technique Development
Technique is optimally developed with load of 85% plus of 1 Repetition Max for single repetition.
Enough rest between sets ensures that each repetition is fresh so your Technique is spot on.
The number of sets performed is dependent on muscle fatigue. Once it sets in, Deadlift Technique is terminated for the day.
Powerlifters
Powerlifter are unique, in that they use the Competition Lifts as training movements.
Olympic Lifters
This group doesn't crank out set of moderate to high repetitions of the Snatch, Cleans, Jerks or the Clean and Jerks. Repetition in set are kept low.
Pole Vaulter
They don't vault for repetition, let a long perform vaults with a weight vest and perform repetition.
The same applies for Basketball, Baseball, Football, etc.
Increasing Strength In The Deadlift and Other Powerlifts
The Westside Protocol is on target with its use of Auxiliary Exercise that work the muscle involved in the Deadlift: Good Mornings, Back/Hip Extensions, etc.
Dr Tom McLaughlin's Bio-Mechanics Research
At about the same time that the Westside Training Protocol began, McLaughlin's research come to the same conclusions. The Competition Lift was only performed for Technique Training/Development. It was not employed as a Strength Exercise to increase Limit Strength in the Lift.
To reiterate, Auxiliary Exercise were use to develop Limit Strength in the movement.
Summary
1) Technique is optimally developed in Competition Lifts with days specifically set up for it. The use of single repetitions with 85% of 1 Repetition Max, with enough rest between each set so each repetition is pulled correctly.
2) Strength for a Competition Lift is increased with the use of Auxiliary Exercise that works the same muscle and have a similar Strength Curve movement.
Final Thought
With any new method, it should be performed is the "Off Season"; which allows experimental time to learn how implement it.