If you are looking to build strength on the deadlift I recommend doing full dead stop reps as opposed to touch and go. For a lot of people the hardest portion of the deadlift is the initial pull off from the floor. By using touch and go reps you are taking this part out of the lift by using the stretch reflex of the muscles.
As the name suggests the movement should start from a dead stop. Your bar should start on the floor and finish on the floor. You should aim to reset your stance after every rep to in order to try and replicate each rep as much as possible. It will also allow you to start each rep with the bar in the optimal position which is directly over mid foot whilst also allowing you to get into the correct position prior to lifting.
As I said I recommend this approach for building strength. If your goal is repetition and; or time based like Crossfit for example, this approach may not be best suited to you.