De work for upper body works better with heavy percentages than deads or squats. it also does better with 2-3 reps instead of 1-2 like lower body movements. less sets IMO can do just as well. it is also my opinion that most people, even 400+lbs benchers do not need dedicated speed work for bench. they need to do all their training faster and get in more frequency. if you feel you need to do DE work then use bands or chains. use a slingshot on ME days or as part of your RE work.
if you are referencing westside's DE, the book of methods has a general recommendation of 50-70%. IMO newer lifters need to be in the higher percentage while more experienced lifters can go lower, but maybe with more volume. you can hit that 70% with a total of 40-50% of weight and 20-30% chains or bands for the bench.
jim wendler has a book called the max effort method. it states to use 55% for bench for 8 sets of 3 and keep rest to under 60 seconds.
