All the retriever breeds were originally bred for their working/retrieving abilities and the will to co-operate with humans. Selecting and breeding with the right parents is where it all starts and is the foundation for every successful working retriever. But even the best bred dog but badly trained will never become a reliable shooting companion or win a test or a trial.
Why group training? First of all, whether it should be your future gundog or competition dog, they all need to learn to wait for their turn. This means that teaching your dog to be steady and relaxed while other dogs are working is an essential part in one's training since it is not a natural skill dogs have and this is best trained in a group. Secondly, learning from watching other people work on individual problems, meeting other dog people and sharing experiences make a training day both an unforgettable and inspiring event for you and your retriever.
Nevertheless, don't forget that your dog needs to have a certain foundation mentally and training wise to join and benefit from group training. Therefore, I think that dogs should be at least 12 months old to start training in groups. If some bad habits or severer problems have already manifested themselves in your dog's behavior or work, individual training is the best way to work on those problems, as it usually takes longer to get rid of them again.
Whatever kind of training you prefer, I am happy to help you. For further information click here.