There is a clear pattern in the literature that indicates a strong relationship between dose of therapy and the outcomes. In other words, the more times a week you meet with clients, the better they do (Bruijniks et al., 2015; Cuijpers et al., 2013; Reese, Toland & Hopkins, 2011).These results do not sound promising for the idea and ethics of meeting with a client once a month, and suggests that the ethical course of action in a case in which a client cannot afford therapy is either to refer him out to a therapist he/she can afford to see at least weekly, or to lower your fee. Doing otherwise is perhaps doing more harm in that it is providing the illusion of helping, while in fact the therapist may be doing little good, and certainly not as much good as he/she could be doing.
These results are very much in line with what we know about the brain and plasticity that indicate that repetition matters crucially for learning and for inducing neuronal change (Viviani, Nagl & Bucheim, 2015).
Bruijniks, S. J., Bosmans, J., Peeters, F. P., Hollon, S. D., van Oppen, P., van den Boogaard, M., … & Huibers, M. J. (2015). Frequency and change mechanisms of psychotherapy among depressed patients: study protocol for a multicenter randomized trial comparing twice-weekly versus once-weekly sessions of CBT and IPT. BMC psychiatry, 15(1), 1.
Cuijpers, P., Huibers, M., Ebert, D. D., Koole, S. L., & Andersson, G. (2013). How much psychotherapy is needed to treat depression? A metaregression analysis. Journal of affective disorders, 149(1), 1-13.
Reese, R. J., Toland, M. D., & Hopkins, N. B. (2011). Replicating and extending the good-enough level model of change: Considering session frequency. Psychotherapy Research, 21(5), 608-619.
Viviani, R., Nagl, M., & Buchheim, A. (2015). Psychotherapy Outcome Research and Neuroimaging. In Psychotherapy Research (pp. 611-634). Springer Vienna.