The last 20 minutes matter if your goal is performance, or muscular hypertrophy. Then yeah, those last few reps, done through clenched teeth and sweat dripping

The last 20 minutes matter if your goal is performance, or muscular hypertrophy. Then yeah, those last few reps, done through clenched teeth and sweat dripping in your eyes, are the ones that matter. If it's for health and well-being, it's the fact that you're doing anything at all - hence "the first 20 minutes" rule.