One 2 one can be a very effective way to help improve your goalkeeper skills. Many goalkeepers know that during your career you may develop areas that need more focus in training.
Goalkeepers can fall into a trap very easy and develop bad habits. If these bad habits are not recognized early they can become a problem.
Attending goalkeeper schools is a great way to develop as a goalkeeper, but sometimes a goalkeeper needs one2one coaching to work closely on different techniques.
For example if a goalkeeper struggles with kicking(distribution) having an one2one can work solely on this technique to help iron out any bad techniques and install confidence in a goalkeeper.