Some years ago, one-on-ones went from being an oddity to the keystone of progressive management. I’ll give credit to Michael Lopp, who wrote about them back in 2010. I’ve had (literally) thousands of one-on-ones at this point, and I can’t imagine a world in which they aren’t the backbone of an engaged professional relationship.

This week, though, I learned of yet another reason why they’re really important. I was talking to a developer who left a job because they were frustrated with how their manager assigned work. It seemed like the friends of the boss got all the good assignments, and everybody else got the scraps. People who don’t trust their managers don’t stick around, and a manager who plays favorites isn’t going to maintain the trust of the people who report to them. Anyway, I asked this person whether they had one-on-ones with their manager and I wasn’t surprised to hear that the answer was no.

Obviously, one-on-ones would have provided a venue for this person to ask about the manager’s strategy for assigning work, but what I realized is that the lack of one-on-ones created an environment where bias thrived. One-on-ones insure that everybody gets regular face time with their manager. This is obviously true, but I think its importance is largely unrecognized.

A manager who doesn’t have one-on-ones is going to spend all their time talking to the people they already have the best relationships with, and those people will inevitably receive more mentorship and more sponsorship over time. Often, this will be based not on performance but rather on shared interests outside of work, a similar sense of humor, or (ahem) demographic similarity.

Scheduled one-on-ones are an important means of preventing this pernicious means of unfairness creeping into the workplace. Managers are people just like anyone else, and they’re going to gravitate toward some people more than others. Putting measures in place to hedge against the problematic aspects of human nature is a big part of a manager’s job.