I personally think that Miracle-Mineral-Supplement does have great benefit with regards to heavy metal and non-organic detoxing; but, I think that its benefits are extreme with regards to pathogenic cleansing.
So, you bring up a very interesting question. If Miracle-Mineral-Supplement kills the pathogens relatively quickly, then why do people still get such great benefit days, weeks or even months later? hmmm....
Well, according to one school of thought called Pleomorphic Biology (usually regarded as a kind of hocus pocus biology by the Science world), when our cells die they can actually devolve into yeast, fungus and then eventually mold.
This is considered the body's own process of decomposition, and represents nature's own way of returning something that is terminally out of balance (a badly compromised body) back into balance (by returning it to it's original fundamental elements). It is basically the fermenting of the body.
Before it gets to that state, though, the body fights off this process over and over again ... trying to return to perfect balance (an alkaline state). Miracle-Mineral-Supplement gives the body a kick-ass way to head in that direction ... but as soon as we ingest anything that tends to return the body to an acid state, the fermentation process speeds up again, and the pests return. Then the MMS knocks it back or out again ... and on and on and on.
The only way to finish off the process and truly return the body to balance (alkaline state) is to stop ingesting stuff that returns us to an acid state, and turn spiritually and emotionally to a peaceful way too. These actions will then allow the MMS to keep cleansing deeper and deeper into the body, and relieve it from having to oxidize stuff that was just recently added to the body.
The more balanced the body becomes, the more resources it has to remove inorganic pollutants. So, I do think that the MMS has a longer term benefit of getting rid of this stuff (such as heavy metals, etc...), but only as the body returns to balance. And, it probably has some additional direct chelating effects also.
So ... that is what is happening from the Pleomorphic point of view.
From the viewpoint of standard biology, I would say that different pathogens have different survival mechanisms in the body ... so maybe they are surviving in different stages or states for longer than one would expect ... and the longer term MMS use is just knocking them out as the crop up. Or, maybe as you said, it wipes out ALL pathogens in a few days, and thereafter it is helping to remove inorganics for a long time ...
(I'm afraid I don't really believe that ... I have observed for too long how good I myself feel on MMS and how quickly the wrong food can cause some pathogenic symptomology...and how quickly it can be knocked down again with MMS.)