you have to take into account some people metabolize methadone much faster than others, i think this is a big factor
the longer you wait the more likely you will get a stronger high, but you probably don't want to put yourself through painfull, aching muscles, restless legs, runny nose, diorrea, hot cold flashes and cold sweats (to name a few things) just to get a short lived high
"60mg IV morphine is approximately equivalent to 20mg methadone in chronic users. "
"Methadone (chronic) 1.35 mg
Morphine (IV/IM) 2.5 mg" source wikipedia
i didn't calculate, but off the top of my head i would say its closer to 35mg methadone in cronic users=60mg morphine IV
i'm sorry i'm always so argumentative, i've allways enjoyed playing "the devils advocate" in a way, its a bit of a bad habit of mine, but at the same time i think its healthy to challenge ideas, discuss, give personal experience and so on
for instance in my personnal experience i've got a very pleasant high and a nice rush from 100mg morphine IV if i wait 24+ hours since dosing my methadone (when i used to take 80mg/day)