Chronicles of Thomas Covenant/WMG

The Land is, in fact, either some kind of manifestation of humanity's global, unconscious mind, or in some way linked to it.
Evidence for this is that first of all, everything in the Land is in some way a manifest part of human nature, as has been more or less stated as such in the books. For instance, Lord Foul the Despiser is the manifestation of human self-despite (which is why he can't be killed - to quote Covenant: 'You can't kill Despite.'). More than this, as the series goes on we see the land feeding back into human minds on Earth, for instance creating a group of mad cultists in the real world that worship Lord Foul, and attempt to sacrifice Covenant to him.

This also explains why the difference in the speed at which time flows in The Land versus the speed at which time flows in the 'real world' is never constant. You can't simply say that ten years in the real world is one hundred in the land, as it has been shown to wildly shift between twenty years being equal to about thirty, and a decade being equal to millennia. However, if the nature of the human subconscious as a whole determines the nature of the land, then the rate of change in the general human subconscious determines the rate at which time flows in the Land. Some humans may also be more strongly linked than others, perhaps even with anyone holding White Gold being the most influential ( as evidenced by Joan's insanity causing temporal distortions in The Land from her bed in a psychiatric unit, while she was holding her Wedding Ring ).
 * "Twenty years being equal to about thirty"? Where? I think it has been established that 1 day in the real world = 1 year in the Land (give or take some, as the seasons don't correspond to any specific times of day). A decade in the real world has been shown to be roughly 3500 years in the Land, which is the time gap between each of the sub-series. From the start of the caesures in the Land, we can calculate that Linden gave Joan her ring back some 100 days before the start of the Last Chronicles, which fits with everything else. It all fits together (save for times of day and seasons).

High Lord Kevin is another transplanted Earthling.
Because in a world of Bereks and Mhorams and Saltheart Foamfollowers, a bog-standard name like 'Kevin' demands explanation.
 * Jossed. In Against All Things Ending the ghosts of all the Old Lords appear in Andelain, and Berek, Damelon, and Loric all regard Kevin as their own flesh-and-blood descendant. That his name is also a real Earth name may just be coincidence- or he might be named after a transplanted Earthling we never heard of, for whatever reason. In any event, he's pretty clearly a native of the Land.

When the Elohim say 'the world has ended now'...
...they aren't messing around. No last-minute heroic exertions, no appeals, no second chances. The Land. Kaput. For our time-travelling heroes, this only puts an upper limit on how far forward they can move. But it does raise a bigger crisis -- if Lord Foul's escape is inevitable, what kind of a man will he be when he does so?
 * Er, Foul isn't a "man" at all. Depending on what view of the Land you take, he's either the God of Evil, Covenant's Enemy Without, or the collective Enemy Without of everyone, and in any case, is pure evil. If he successfully escaped the Land, it would be bad news for everyone (which is why the Creator stuck him there in the first place).

Stephen R. Donaldson is a troper.
Where else would he have gotten the idea to make Covenant a Time Lord?

The Land is a Lotus Eater Machine.
The old man in the ochre robe is some sort of benevolent Mad Scientist who sticks emotionally scarred people into his Lotus Eater Machine so that they might work out their psychological issues in a controlled enviroment. Lord Foul is just a challenge set up by the old man to give his involuntary "patients" a challenge.

Hurtloam is a psychedelic drug.
After Lena rubs hurtloam on his skin, Covenant spends most of the series noticing that sounds now have color, colors now have smells, et cetera. This is a common effect of LSD and similar drugs. It could be that his perception that his leprosy is all better is itself just a drug-induced illusion. After all, nerves don't regenerate.

The Worm of the World's End is a baby universe
Supposedly the Creator had to include something like the Worm of the World's End as part of the Land because he wanted to create a "living" world, and all living things have to die someday. However, there's something else that living things do besides die: they reproduce. In order for the Land to be alive, it has to be able to have a child and then get out of the way so the child can become an adult. The Worm hasn't so much been "sleeping" as gestating - and now it's awake and ready to be born. When it's finished consuming the old world, it'll use all that energy to become a new one and start the cycle over again. And I suspect that Jeremiah is going to be involved somehow - it's not just because of Linden that the Land's remaining defenders (such as the Ranyhyn and the Dead) have been willing to sacrifice everything to save him.