The length of time to heal is different for everyone. I was very ill, more than most people, past the point of fatigue, definitely in burnout, so 3 years is not uncommon for that degree of illness. Everyone's body chemistry is different; I may have tons of mercury while you have low copper, for example. Because NB works by the body kicking out the toxins on its own, we just have to wait for the body to go at its own pace. The body won't push too many toxins out at once, it cannot handle that. I would say it's more like a dripping faucet - it seems like it might take forever but then we feel big shifts every once in a while. It is not fun to have to live in the dark, not knowing how long it will be. But, because things improve constantly, and you are on the path to heal (and not getting worse), it's worth the not knowing. Some practitioners will give you an idea of how long it'll be, but even for them it's a best guess.