As far as the Royal Marines are concerned, the over grasp pull-up is still the best muscular exercise to really test someone’s strength and determination.
For a Marine Recruit, 5 should be a minimum by week 9 of training. As a trained Marine, any less than 10 is shameful. 18 will get full marks in an RMFA (Royal Marines Fitness Assessment) – 20 plus is a good score and one which Royal Marines Physical Training Instructors would be proud of.
Technique consists of pulling up from a dead hang, bringing the chest to the bar, then lowering until the arms are again straight. Any kipping/popping of the body for momentum is not allowed.
For my secret of training to get up to 20+ pull-ups easily check out my PRMC pack from Commando Conditioning.