Ehlers et al. published a good study in the March 2014 edition of The American Journal of Psychiatry in which they compared the following treatments for PTSD:
1) 3 months of regular weekly CBT
2) 7 days in a row of intensive CBT (up to 2 hours daily)
3) 3 months of weekly supportive therapy
4) waiting list control
They found similar good treatment results, after 40 weeks of follow-up, in the regular CBT and the intensive CBT groups, with a slight edge for better response in the regular CBT group. Total remission in symptoms occurred in 50-70% of these groups, compared to only 30% in the supportive therapy group, and no change in the waiting list group.
Once again, a weakness in these CBT studies is a failure to account for the amount and quality of homework done. Possibly the regular CBT group had more frequent reminders to keep up with homework tasks and exposure activities, which is a reason why they did slightly better than the intensive CBT subjects.
What I take from this study is, first of all, CBT techniques (or related techniques which involve similar practice and exposure) are imperative, regardless of other supportive techniques also used.
Second, I think there is a role for both intensive CBT and longer-term weekly CBT. It could be useful to have a regular course of CBT with at least one week of intense weekly sessions as well. It reminds me of any other skill to learn, such as learning a foreign language, learning to swim, learning a musical instrument, etc. : regular lessons are great, but an intensive week-long program could give you a huge boost, in terms of skills, habit-building, and interested devotion to the work. In both of these cases, much of the progress will be a result of diligent daily practice and homework, over a period of months.