Some studies have suggested that 30 hours or more per week is necessary for maximum effectiveness of ABA-based teaching strategies. Although this is questionable (it certainly depends on what's being done during those hours, for example), it is certainly the case that the more hours a week a child receives therapy, the more progress will be made, up to a certain point.

One-on-one therapy is extremely important in most cases, particularly at the onset of therapeutic services. After all, if a typical, everyday environment is sufficient for a child to learn adequately and at a typical rate, then one would not need behavioral intervention. One-on-one therapy in a controlled environment is essential early on to establish rapport between a child and an individual therapist, and allows the therapist to control your child's motivation and use it to your child's advantage. For example, if there is no one else in the room, and no toys freely available, the child is more likely to attend to the therapist and emit behavior to gain access to items that the child is motivated to receive. Once certain skills have been strengthened and generalized, one-on-one becomes less essential, and other socially-related skills can be addressed more easily. Even then, one-on-one therapy is the most effective way to produce learning quickly and reliably.