I kept a book like this, but called it simply my Leader's Book. I also required my PSG to keep one of the Soldiers as well as the two NCOs under him kept one for each of their squads or those Soldiers they were responsible for counseling. It helps develop them as leaders and grwo as NCOs as well as keep track of the progress or shortfalls of an individual. Now what I required them to keep in it was the ERB enlisted Record Brief of their Soldier, Strip map to their house incase of missing formations or emergencies, copies of the last three counselings or counselings for on the spot corrections as well as good counselings for doing outstanding jobs. They also had to keep copy of the EMT-B certificate but were were medical platoon. Alot of it you can tailor to the type of platoon you are. Also PT cards from last two pt tests are good as well. More or less it is really about you learning who your Marines or Soldiers are and how they can achieve greatness by following up with them. the biggest thing I kept and made them keep was a short bio of the person and their short term and long term goals as well so I could do my best to help get them where they wanted to be.