IIf there’s one piece of “Mad Men” office culture that still holds up today, it’s the shows’ spot-on depiction of work friendship — the distinctly modern way we bond with colleagues to the point where they become a kind of twisted surrogate family.

Again and again, the lead characters of “Mad Men” lean on each other instead of their families or partners for support and camaraderie. The deepest, most honest relationships on the show seem to be between colleagues, often at the expense of family. And no one has many friends — or much of a life — outside of the office.

The friend thing was laid bare in the show’s final season — and definitely in its last episode — in the moment when Don Draper, the show’s lead character played by Jon Hamm, owns up to the moral horror his life has become.

“I broke all my vows. I scandalized my child. Took another man’s name. And made nothing of it,” he tells Peggy Olson over the phone, choking back tears.

That Don confessed his sins to Peggy — a coworker — in a suicidal cry for help, shows just how close they’ve grown over the years.

Don and Peggy bonding in Season 4

The seven seasons of “Mad Men” took place in what can often seem like a foreign country — the hyper-sexist, racist, homophobic and patriarchal U.S. advertising industry from 1960-1970. Things have changed. Yet the ways the show portrayed work friends and work-husbands and work-wives seems even more apt now when workers are staying single and child-free longer and devoting more and more of their time to the office (or connected to it via phones, chat, etc.)

The show is the key dramatic counterpoint to a recent batch workplace comedies — “The Office,” “Parks and Recreation,” “Silicon Valley” — that comically grapple with the uncomfortable fact that we spend most of our adult lives on the job.

Plenty of us clock more hours with our colleagues than our partners, friends or children. More of us probably have work-husbands than husband-husbands. If you’re spending 50-80 hours at work, there’s little time left for real relationships.

In terms of our work lives, that’s not such a bad thing: There’s evidence that our office friends make us better and more productive workers. “Studies show that employees with a best friend at work tend to be more focused, more passionate, and more loyal to their organizations,” writes one researcher who’s looked closely at workplace relationships.

But in terms of our lives-lives, I’m not so sure. At the end of the day, the bonds we make at work are tenuous — anyone who’s ever promised to stay in touch with former colleagues when they leave for a new job knows not to take the “forever” part of BFF too seriously. The bonds of the office Slack do not bind us in the real world for long. Indeed your access to the Slack will be cut off along with your employment once you get fired or move on.

Of course, lots of different kinds of friendships are situational — I don’t think I’ve talked to any of my high school friends outside of Facebook in years. But friendships at work are also formed in a place of shifting loyalties and hierarchies and, of course, competition. This came across in “Mad Men,” for sure. There was that time Joan, who’s had a strong friendship with Don over the years, voted to kick him out of the firm’s partnership. Her business interests no longer aligned with her friendship.

There are plenty of times these people let each other down or stepped over a “friend” to get a job or a client or a promotion. Yet their work friendships seemed to be the most real relationships these characters had. These people let their marriages and intimate relationships rot. They neglected and abandoned their children.

These characters were at their best, and the show was at its most exhilarating, when they stayed true to each other. When Don and his partners learn that their agency is about to be swallowed up by their corporate overlords at McCann Erickson, they spring into action. Don leads a desperate attempt to retain autonomy. It fails, but there’s a scene where Don, Joan, Pete, Ted and Roger commiserate over mugs of beer that will be eminently relatable to anyone who’s ever toasted the departure of a beloved colleague or commiserated with coworkers after a round of layoffs.

By the end of the series, the support the “Mad Men” characters have given each other leads to huge career success. You get the sense that Peggy’s reaction on that terrible phone call — “Don’t you want to work on Coke?” she asks Don — ultimately helps lure him back to advertising. And, if you read the show’s ending one way, it leads to one of the most well-known ad campaigns ever — this one for Coke. Pete is tapped by an old work-frenemy to grab what turns out to be his dream job. Roger Sterling meets his girlfriend and soon-to-be wife through his work friend (albeit in a kind of creepy way).

In the first half of this last season, there’s a scene where Peggy, Don and Pete sit at a table at Burger Chef, a fast-food restaurant and potential client. The camera pulls back and the three of them look like a family — laughing, talking, eating fries, etc. It’s a little surrogate family. Look familiar?