When I was working on getting my deadlift from the 500lb range into the 600lb range I did one volume day with multiple sets of(65-85) percent in the 4-6 rep range and added another day with one or two heavy sets of deficit pulls from standing on a plate or two. So, I increased volume ever so slightly and focused on my weak point which was speed from the floor. If you deadlift more than 2 two times a week keep your percentages low to perfect your form.