No matter the complexity of the problem, your Speech-Language Pathologist (SLP) should set goals that can be achieved in a reasonable amount of time, usually within 6 months. The duration of treatment depends on the issue the child is working on and can range from a few weeks to a few years. If you have any doubts about the severity of a speech or language problem, it is best to have your child evaluated by a qualified local SLP. I have seen cases where children only had one sound they had difficulty with and it took longer to treat than expected.
Any additional challenge would likely make speech therapy a long-term process. If speech therapy is recommended, the therapist and family will discuss the evaluation results, as well as the goals and expectations of the child's treatment plan. A 2002 study suggested that approximately 14 hours of therapy are needed, on average, to achieve significant progress in improving speech clarity. The content of speech therapy sessions varies greatly from patient to patient due to different capacities and objectives, but most patients visit the clinic once or twice a week for about an hour. The therapist can determine if the child needs speech therapy based on their score.
I have seen children with many speech-related goals, along with additional behavioral problems, make rapid progress and be discharged from services. Some children may need speech therapy for a few sessions, others for a few months, while other families may choose to access support for several years. It is difficult to say exactly how long it takes for speech therapy to work. Others may be hard to understand and could have a speech articulation disorder, a phonological disorder, or childhood apraxia of speech. It is important to ensure that the therapist you choose is qualified to meet your child's speech and language needs.
Fortunately, there are special types of therapists who can help SLPs. A standardized evaluation is a test that compares a child's speech and language skills with those of other children their age. When it comes to seeing results from speech therapy, it really depends on the individual case. Generally speaking, most children will start seeing improvements within 6 months of starting treatment. However, some children may take longer depending on their individual needs and goals.
It is important to remember that every child is different and progress will vary from one case to another.