You can be productive high. It just depends on your body type. I got friends that wanna just sit and eat high while others want to do something and not be a lazy fûck n eat. I've lifted high and it was a great workout. The only dangerous aspect of it is that you don't feel your muscles fatigue. You keep truckin n they just die and you are at muscle failure. One of the best workouts I've had cause the next morning was killer