Therapists help clients in many ways but here are two ways therapists earn their pay.
1. Contraindications. When I taught OT students I used case studies to make them to think about the needs of each client. I had students work in small groups to treatment plan for one case and then had them individually treatment plan for a different case on an exam. This allowed me to identify students who knew which solutions from the 1st case could be used with the 2nd case.
For example, the 1st stroke survivor had a tight arm that did not want to straighten to allow him to don a shirt. This client should be taught to use gravity to relax the arm by hanging it between his legs before dressing. On the exam I gave them a stroke survivor who had flaccid shoulder muscles that could not hold the arm in its socket. Hanging the arm between the legs was contraindicated because it can damage nerves by stretching them. A client should not have a brachial plexus injury added to the paralysis created by a stroke. Students lost double points when they blindly used protocols that endangered a client. The phrase "all strokes are different" can irritate stroke survivors, but a therapist who thinks all strokes are the same is dangerous.
2. Nothing Works 100% of the Time. When science finds a new cure it never saves 100% of the people. A treatment protocol is considered successful when it cures a majority of the people. It is a therapist's job to figure out what to do when a client does not respond to a protocol that has succeeded with other clients. For example, the PT who is treating me after my knee surgery taped my knee. I never dreamed the tape would aggravate the constant burning I feel in my foot. When the burning sensation crept up my calf to my knee I took the tape off. She will have to find another way to increase my knee stability. Apple would lose business if updates they send to iphones work on only 80% of phones. Humans have to live with the fact that we are not identical clones that respond identically to protocols.