The things studied in 5 step sparring are covered, but counter techniques are more prevalent. Therefore, learning to reduce the time between blocking and attacking becomes more important. Learning to make a single, explosive attack is important. Also, the attacker learns to reduce telegraphing of intent to attack while the defender learns to recognize incoming attacks and react accordingly. Not very much.
Techniques are to be stopped short of damaging contact.
However, this is a little dangerous. Also, contact from attacking or countering techniques should be mere touching, and no pain should be felt at all. The lower the skill of your partner, the more danger there is to you. Beginners throw techniques in an odd fashion, have no control, and are dangerously unaware of the potential for injuring someone. Because of this, many instructors ask their expert students to pair up with the beginner students, since the higher ranking students should be able to protect themselves better and prevent injuries while allowing the beginners to learn.