When in doubt, continue the doubt. And “The Walking Dead” -- as TV’s most disturbing, reductive, dystopic franchise-without-end -- has entered the stage of life beset with doubt. Where to go. How to get there. Whom to kill. How to tease.

These have been the big dynamic plot drivers of the sixth season, which ended Sunday night. They’ve stalked the series at every turn, every episode. Two steps forward. Three steps back. No reason why the habit, now a tiresome one, shouldn’t continue right through to the end of the sixth season finale, which it did.

Fans waited all season to see Negan -- played by Jeffrey Dean Morgan -- who is far and away the most anticipated villain since David Morrissey’s Governor, and finally see him they did. But not before theories abounded, and questions multiplied. Would Glenn (Steven Yeun) die? Surely he must. That’s how the comic book series figured it. Starring Lucille as the baseball bat from hell, Glenn is supposed to meet his end this way, in the Robert Kirkman graphic novel series.

Instead, Negan plays “eeny, meeny, miny, moe” and his bat came down on an unknown head. Maybe Glenn’s. Maybe someone else’s. Cut to black ... Season ends. You’ll have to wait seven months for answers, and even then they might not come.

This is how TV-without-end works. You cliff hang the fans. Make them wait, make them wonder, and then make them wait and wonder some more. Who killed J. R.? Wouldn’t you like to know.

In the age of social media, TV-without-end makes fans barter endlessly in meaningless suppositions -- the way they did last week when it appeared that Daryl (Norman Reedus) died at the end of the March 27 episode, “East.”

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Maybe Glenn, maybe not. This is the kind of speculation “The Walking Dead” now trades in.

There’s one obvious reason for this gamesmanship. “TWD” wants to suggest to fans that the Kirkman series is not necessarily a road map as much as a general idea -- something not to be slavishly followed but merely casually followed, or followed when convenient. This allows “The Walking Dead” latitude to do what it wants when it wants, without spoilers preceding every word or action.

Negan, the subject of their endless chatter until Sunday, made the entrance he was supposed to make Sunday night, as established by the comic book series. It was a long entrance, almost an interminable one.

Like the comic book, he wore the dark leather jacket, but was not clean-shaven (Kirkman’s Negan was modeled on a clean-shaven Henry Rollins). Negan was a used-car salesman before the apocalypse, and maybe endless rejection along the lines of “no, I’m not gonna pay that kind of money for that piece of junk” twisted his sense of proportions, or made him homicidally violent. “The Walking Dead” doesn’t afford many opportunities to explore his psychological profile, nor did it last night.

He clearly enjoys deliberating fates, and he talks an awful lot. He is a man of words, too many words. This scene lasted 10 or so minutes. Talk, talk, talk. Negan had clearly seen far too many westerns in the pre-walking-dead world.

He was Liberty Valance tripping up Jimmy Stewart, or Jack Wilson in “Shane.” Or maybe he was just every movie Lee Van Cleef was in, from “The Good, the Bad, and the Ugly” to “A Few More Dollars.”

He was a bad guy -- the bad guy:

“You built something. You thought you were safe. But the word is out. You are not safe. Not even close.”

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Comic book fans know where this goes from here, or think they do. TV fans don’t, which is clearly shaping the decisions “The Walking Dead” has increasingly made, especially during the sixth season.

It is sowing doubt, giving viewers the sense that maybe their assumptions were wrong all along. Someone died Sunday night. You’ll have to wait seven months to find out.,

What this says -- what it has said -- is that AMC and the most financially important series in its history, need to keep the gravy train rolling, perhaps indefinitely.

After six seasons, many series would be well into their endgame. Like “Mad Men” or that other series where Morgan has also been starring -- “The Good Wife,” which ends in a few weeks -- they’d be laying the groundwork for the last scene of the last episode by now.

But “The Walking Dead” has no such luxury. Instead, “The Walking Dead” has miles to go before it sleeps. If AMC had its choice, this series would never end, and indications so far is that it won’t.

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“The Walking Dead” will continue on into the future, year after year, ad infinitum. Cast members will come, and go. One day, the series might even outpace the book, like “Game of Thrones.” Fans will grow old wondering how this ends, or if this ends.

And as the sixth season wrapped, and Negan wielded his bat over an unknown victim, that’s precisely the danger that now faces the show.

“The Walking Dead” is no longer about walkers, but people. The tropes are no longer necessarily horror ones, but western ones (spaghetti western ones, in fact). Walkers are now incidental to the outcome. They are part of the window display, nothing more. To fill full seasons, plots are stretched, sometimes repeated with slight variations. Because “The Walking Dead” is so well produced, it’s easy to overlook the patterns, and gimmicks, and especially the stretch marks.

But they’re there, and while they’re a sign that the series is getting tired, there’s only seven months to go before the seventh season begins.

No time to rest, and miles before it sleeps.

Endless miles.