For strength protocols to be optimal, flexibility should be included. This is difficult with normal percentage based training as one rep maxes tend to fluctuate a lot on a weekly basis. This will make the percentages based on the one rep max unrealistic. A rate of perceived exertion (RPE) type approach is a lot more realistic as the rpe number itself is not affected by the weekly fluctuations.
For that reason, we prefer RPE based training over percentage pased training. In the picture underneath you´ll see our interpertations of the RPE numbers.