The "dose" of counseling or psychotherapy necessary to produce meaningful improvement is unclear. In research with methadone-maintained patients, counseling and psychotherapy have typically been offered once a week, but patients have attended, on average, only once every 1.5–2.0 weeks (Woody et al. 1983, 1985, 1995). However, at the same time, patients were receiving daily doses of methadone, so the overall intensity of therapy was high, since it involved daily or near-daily visits to the facility. A study evaluating the optimal frequency of drug counseling with or without additional services for methadone patients found that they did significantly better when they received weekly drug counseling as opposed to brief monthly counseling. Outcomes of weekly counseling were further improved when it was supplemented with individual psychotherapy or family therapy provided on site (McLellan et al. 1993).