I find with my OCD patients that often beginning with gradual exposure (for those patients who could not tolerate flooding) is effective in reducing the frequency of the compulsion. Then when the frequency of, for instance handwashing, is quite low, massed exposure (flooding) is effective in eradicating the remainder of the behaviour. I actually predict ahead of time that the patient will try to develop more efficient rituals but indicate that "their ocd can run but it can't hide" and that eventually they will resist their compulsions. In effect, the relief that the patient has after decreasing checking from 35 times daily to 2-3 times daily is a significant therapeutic effect in and of itself. Many of my patients find that they retain some residual compulsions and that, because their level of distress about those compulsions has significantly abated, they wind up lacking the motivation or need to eradicate the remaining symptoms.
Interested in your thoughts...