Is this one question or many?  If you see a therapist, how many treatment sessions are you likely to need?  Sometimes that's a little like asking "If I go on a journey, how long should I travel for?"  Happily though, we do now have enough research evidence to be able to respond fairly helpfully to this "how many treatment sessions?" question.  To give useful answers though, it’s probably sensible to break the very general “how many sessions?” query into a number of more targeted sub-questions.

I average a little over three hours weekly scanning medical and psychological journals on the internet. Typically I zoom through the article titles looking for anything relevant to stress, health & wellbeing. If something seems interesting, I read the article's abstract.  I may well then download it to my bibliographic database - I use EndNote. Currently I have well over 19,000 references stored and the number grows steadily.  Sometimes I'll get hold of the text of the full article - by subscribing to the journal, buying the article, searching for the author's academic website, or emailing the corresponding author directly.  I use this information I glean to improve my treatment of clients who come to me for help, and as a basis for talks and articles.

Here are six studies relevant to improving psychotherapy outcomes.  Brewin et al report on using imagery-based interventions to help people with depressioin.  Lydiard et al highlight the importance of sleep-related disturbances as a treatment target in PTSD.  McCrady and colleagues show that working with couples rather than just individuals seems more effective when using behavioural therapy to help women with alcohol use disorders.  Geerts et al describe rather amazing research investigating "The role of parental bonding and nonverbal communication in the short-term treatment response was investigated in 104 depressed outpatients. At baseline patients completed the Parental Bonding Instrument. We registered the nonverbal involvement behaviour of patients and interviewers from video recordings of baseline clinical interviews and calculated the convergence between patient-interviewer behaviour over the interview ... As hypothesized, low maternal care and high paternal overprotection predicted a poor response to an 8-week treatment.  Maternal care was positively correlated with nonverbal convergence. Moreover, convergence moderated the relationship between maternal care and the response to treatment: Lack of convergence between patients and interviewers turned out to annul the positive effects of maternal care on the treatment response.