I told a few friends at my clinic about using my take home bottle this way, and they all tried it and now do it every weekend too. One thing I might mention is that I (and the friends who also do this) are all at relatively low (non-blocking) dosages. IME methadone is similar to suboxone in that the only way I can get a nice consistant mood lift from my dose is to keep it low (40 mg). If you're taking enough methadone to saturate your receptors (I.e. a blocking dose), I'm not sure if plugging would really be that much better, though it would surely ensure a quicker onset. Lastly, I'm lucky in that my clinic dispenses the methadone in a 10mg/mL solution, so I can suck it all up in one go with an oral syringe. When it comes to plugging, I've found that it works best when you use somewhere between 4 and 10 mL of liquid (regardless of the substance). If your methadone is 1mg/mL, I wouldn't really bother with it.