The article "First LSD Study in 40 Years Finds Therapeutic Potential" relates the finding that people faced with life-threatening disease (typically cancer) seemed to have slightly reduced anxiety after 2 decent sized doses of LSD (200 mcg) in combination with psychotherapy. This replicates research from the 1960's and is basically identical in focus to the current psilocybin cancer project at Johns Hopkins.
Having personally received the psychological benefits of psychedelics drugs, I can see (sample of one) that this could be a very fruitful area of research, but I am always a bit surprised when they get significant benefits with just one or two exposures to the drug. I guess I was a little bit slow on the uptake. Once the "right" layers started to peel away, I'd say it took about 10 sessions to completely work thru everything.