Its true.. Workouts can be brutal.
For example, do not workout at home with a giant barbell. If you do, always do three reps less than failure because I am talking from experience.
Imagine that you are bench pressing a very heavy bar and all of a sudden you are one rep less then failure, your shoulders and arms are so fatigued now, you can't push the bar up to place it back on the rack.
Yeah, you guessed it, the bar will be on your nect or hanging on your chest while your feet are sky high in the air trying to send momentum to lift the bar back up.
And that is exactly why dumbells or bodyweight exercises are recommended workouts if you are doing it at home..!