Feasible is an interesting word choice. It's feasible but I wouldn't recommend it unless it's necessary. Everyone has their own story. As FUBAR has touched on, different phases of withdrawal are of variable difficulty to different folks. For myself, all of it was relatively easy from 120mg -> 5mg at which point I jumped off. The most painful part for me was going from any level of Opioid to absolute zero. Absolute zero really increased my cravings, withdrawal syndrome, everything.
It's common practice as you probably know for Methadone clinics to immediately half-dose individuals who test positive for Benzodiazepine usage until they can produce a clean urine and/or a lie of sufficient quality. I've always believed this policy to be more detrimental than helpful to the patient in question, as a one time dosage of, say, Diazepam (Valium) or Chlordiazepoxide (Librium) can cause a positive result for up to 4 weeks. This is plenty of time for the patient to continue a downward spiral into oblivion and for many, such an event marks the end of what might have otherwise been relatively successful maintenance treatment.
The takeaway here, I feel is that you shouldn't do this sort of thing unless there is a good reason for it. Slower is always better. Even if you can "handle it", a more rigorous withdrawal experience is a major impetus for return to daily/chronic usage of street Opioids. Reducing the dose of any patient immediately by 50% is bound to be emotionally and physically traumatic regardless of the individual.
