I think they went the opposite way g following revised NICE guidelines. When I first presented for treatment, I was smoking approx 2 bags of medium to weak gear, with the odd one IV'd. Historically, Ive always been seen patients strted and maintained on 30 - 40mgs which achieves nothing, the patient is able to carry on using on top with the meth to potentiate shit gear or to cover them when they couldn't afford to score. Despite my habit being relatively small at the time (10 years ago I was getting thru an 8 ball every 72 hours) the consultant put me on a 'therapeutic dose', deliberately raising my dependence until I could tolerate 70mls of methadone which would saturate my receptors and prevent even the best street gear from having an effect.
To give her some due, it worked, as the only time I could get an effect from the drug would be over a weekend when I could skip my takehomes. It only took a month or 2 to reduce my heroin use from daily to once a week, then fortnightly, and although I rarely go more than 3 weeks now without scoring, the blocking action of the methadone, on average, has reduced my usage from daily to 17.3 times a year. It was only once she had broken the pattern of my regular use that she agreed to reduce my methadone with a view to total detoxification. Im down t0 50mls now which means Ive been fucking about a bit more than I should now the meth isn't blocking the gear but I know I need to watch it once it goes down again, else ill be creating unnecessary pain and discomfort through the final phase of my reduction.
8( 
