Charlie, SE in this case means speed endurance or strength endurance? This is an interesting point and says something about intensity. Many readers look at someone like Ben, who I believe you stated rarely if ever went fewer than 6 reps, and use a 6RM for the upper end of their workouts. For the ‘typical’ athlete that is about 85% of 1RM. For elite sprinters/athletes like Ben with optimally developed SE, pushing to a 6RM could have actually been 90% of 1RM. Does that seem consistent with Ben’s case?