In Metallica’s frenetic 1983 ode to headbanging, “Whiplash,” the band’s guitarist and lead singer, James Hetfield, barks, “We’ll never stop, we’ll never quit, ’cause we’re Metallica.” Somehow, across four decades marked by success but also death, addiction and at least one very public near-implosion, the band has kept its word.

This year, Metallica released its 11th full-length studio album, “72 Seasons.” Its debut LP, “Kill ’Em All,” also turned 40, just days before the quartet arrived in New Jersey for the first North American date on its M72 World Tour. Metallica isn’t the only band doing stadium tours even as its members pass 60, but not every band makes its bones slamming through songs that regularly top 190 beats per minute.

That tenacity was evident on a Friday night this month at MetLife Stadium as the tour touched down in East Rutherford. Drums pounded. Riffs chugged. Solos melted the faces off an all-ages crowd of about 80,000, dressed almost exclusively in black.

But how does a band keep it fresh after, by the drummer Lars Ulrich’s count, performing “Master of Puppets” 1,697 times onstage? The answer is by constantly “mixing it up,” said Ulrich, who creates the band’s set lists the day of each show — a “safeguard,” he added, “against ending up on autopilot.”

That may sound obvious, but it wasn’t always the case. “Thirty years ago, we took going out and executing a set really seriously,” Ulrich explained by phone last week, when the goal was nailing everything “almost like in a robotic way.”

Metallica — which also features the guitarist Kirk Hammett and the bassist Robert Trujillo — started fiddling with its encores and covers as its catalog kept growing. About 20 years ago, on the “St. Anger” tour, the group set an ambitious goal: Never again play the same set list twice.

Dates on the M72 tour, which run through September 2024, are organized around “no repeat weekends,” featuring two shows in each city with two different lists and two different sets of opening acts. (The band will play two weekends in Mexico City, where the tour wraps up.) The stage is doughnut shaped, with fans standing inside and out; the setup allows band members to face different parts of the crowd at different times, and it relies on four drum setups, creating multiple front rows.

“Mixing it up” with the set list itself is a surprisingly complex affair. Metallica productions go big, and the band’s elaborate program of pyrotechnics, lighting and interstitial audio-video, among other flourishes — the New Jersey show included a drop of dozens of giant black-and-yellow beach balls — has historically discouraged major changes to the list. Having four drum kits this time didn’t simplify things.

Eventually, the band developed what Ulrich called a “slot” system based on the band’s different “food groups” of songs, a reference to their feel and tempo. Slot 1 (of 16) on the M72 tour, for example, will always be an upper-mid-tempo fan favorite — Day 1 at MetLife, it was “Creeping Death” — that has a quickly recognizable opening riff: not too fast or complicated. But the songs in that slot will rotate. Slot 10 should always be a ballad, like “Nothing Else Matters.” The closer is always “Master of Puppets” or “Enter Sandman.”

Ulrich also keeps careful data about what song the band has played where, and tries to tailor the set list accordingly.

“At times it turns into a science” he said. “We’re in Montreal now, and I’ll have all the info for the last 20 years that we’ve played Montreal in front of me. And I can put a set list together where the deeper cuts will not be repeated.”

Certain songs, like “Sandman,” “Puppets” and “One,” are in constant rotation. Ulrich said the band calls them the “toe-tapping favorites” — an odd, and perhaps ironic, choice of words for songs better known for headbanging.

A lot of bands begin to mellow as they mature; by most accounts, that happened to Metallica over three decades ago, enough time for the band to have since come full circle. Like the band’s two most recent albums, “72 Seasons” continues Metallica’s return to the thrash-metal style that defined its early years, and the tour supporting it has thus far followed suit: light on covers and ballads, heavy on the heavy. New shredders like “72 Seasons” and “Lux Aeterna” slot tightly into lists packed with thrash classics like “Seek & Destroy” (1983), “Battery” (1986) and “Blackened” (1988).

Ulrich spoke in detail about the set list from that first night at MetLife and helped decipher some of the notes. These are edited excerpts from the conversation.

‘Creeping Death’

“This is one we would call a fan favorite, and it’s not one that we always play. It’s got really good energy in the riff, and it sits in a kind of an up-tempo place without being so super fast that it just becomes, like, an indistinguishable roar. But it’s got good accents, good dynamics. It’s got a breakdown after the second chorus and the guitar solo, where it goes to a shout-along part where James gets everybody pretty engaged. [‘Die! Die! Die!’]

What makes a good opening song? I mean, ask a hundred people, you get a hundred different answers. So none of this is science. But after a while, you start figuring out instinctively that this song maybe works better than this other song. Often when you are touring on the back of an album, the default is to open with the opening track off the album that you’re touring with. I wanted purposely to not do that, just to sort of challenge ourselves.”

‘72 Seasons’

“’72 Seasons’ is the opening song on the latest album, and it’s also the title track. It has a real forward motion and a lot of energy, and I think it’s really representative and indicative of the head space and the mood and the energy of the new album. So it feels like a great way to kind of introduce what we’re doing these days.

The title refers to the first 18 years of your life; in broad strokes, it’s basically the idea that the first 72 seasons of your life shape who you become, for better or worse — and as you move through life, you’re trying to expand on those experiences, or maybe shake them, get away from them.”

‘Fade to Black’

“We’re all very open about where we’re at with our moods and all of us dealing with various levels of mental health. And that feels like it’s less of a taboo than it was, say, 20 or 30 years ago. I think James, increasingly, is very comfortable onstage talking about how he’s doing and how he’s feeling, and often he’ll send ‘Fade to Black’ off with some personal thoughts or something that relates to how he’s doing in that moment, in the spirit of sending good energy to people who are receiving it from a place of struggle. And the takeaway message is that you’re not alone, and that we’re in this together. I’m an only child. I’ve struggled with being an outsider and a loner all my life. And, you know, being in a band, playing concerts and all that is the best remedy for me to feel that I’m not alone.”

‘Orion’

“It’s one that we have enjoyed playing a little bit more in recent years — we actually opened with it when we played with the Rolling Stones. It has a unique palette and illustrates the different songwriting inspirations and influences that exist within the band. When we’re playing it, the spirit of Cliff [Burton, the band’s original bassist, who died in a 1986 bus crash] is definitely present in the building. And Robert channels Cliff’s spirit in the part that he’s playing so incredibly well. It’s a beautiful, beautiful moment.”

‘Master of Puppets’

“‘Master of Puppets’ is actually the song we’ve played the most live; it’s been a part of every tour since we released it. It got a significant, unexpected boost last year when it became part of the ‘Stranger Things’ finale. And who would’ve thought that a 37-year-old song that’s over eight minutes long and is pretty heavy throughout would resonate in the way that it does with a new and younger generation of listeners? But how crazy cool is that?”

What’s the ‘Hang’ Cue?

“‘Hang’ means basically the songs are connected — that there’s no, like, full stop. It doesn’t go to silence. So it just means stay on a chord. And then the next song comes out of that rather than out of a vocal introduction or a tape.”

The Four Drum Kits

“This is the first time we’ve done a 360-degree stage in a stadium setup. We tried to crack the code on that for years. Everything that we had done always had a center point. We were going down this rabbit hole a year ago, and all of a sudden it was like, Well, hang on, why does the band have to be in the center? And then it was like, What’s the opposite of the band being in the center? And that would be the fans being in the center. And that’s when we came up with the doughnut concept, where you play on the doughnut itself and then the fans are in the doughnut hole. And then, well, where do the drums go? Then the concept of the four drum kits — one drum kit in each of the four different directions — came up, and then it sort of went from there.

You know, all this [expletive] makes a lot of sense when it’s in an email or it looks really good on a napkin. Nine months later you’re in the first venue trying to figure out what the [expletive] you’re doing.”