A strength of systematic desensitisation?

-Gilroy examined 42 patients with arachnophobia, each patient in experiment group was treated using 3 x 45 mintue SD sessions. Control group only have relaxation technique training. -3 months and 33 days later, the SD group was less fearful than control group -A longitudinal study, results collected over long period time. Means that SD provides a long term solution to specific phobias.