I think we all need time to process new information, new skills etc. whether human or dog. If I remember correctly, and approximately, what the study says is that dogs who have more frequent training sessions will acquire the behaviour quicker but the dogs on the once a week regime performed the behaviour better. I know both Juno and I get bored if we train the same things every day. Apart from early recall and sit/stay in the garden most of our 'training' has been an integral part of our daily walks, trips into town etc.