FYI, Freddd theorizes that there are levels of healing, and that a certain amount of folate is needed to pass through each level. But that amount is different for each person according to the state of their health. A very sick person will need more for each level, and for a longer period of time, than will a person who is not terribly ill.
BTW, don't get too hung up on what the "levels" are...I suspect he may have chosen that term simply because it was the best way to conceptualize what he was saying, and also to help categorize the different symptoms that could be manifested when experiencing folate deficiency.
Main point to the concept of levels being that you can't progress with healing unless you've got sufficient folate to drive the process. Also, sometimes you may get sick, get better, then get sick again. But each time you get better, you're better than you were before. It's like going up stairs or a scatter plot graph rather than a straight linear ramp or shot from illness to wellness.
So, say you take 800mcg/day of folate for a while. That's enough to get you you going. But when your body tries to pass through to the second level on that amount of folate, it can't, because the folate is all used up. Or maybe it even stops halfway through the first level because you don't have enough folate to get all the way through that. It's like a car running out of gas. To get where you want to be, you need enough fuel to get there. You have to add more folate. When you do, you will progress until you use up all that folate. And so on, until you've done a bunch of healing. When your body is healed or at least well on the path to healing you can reduce the dosage. Or that's the theory.