Google is famous among engineers for “20 percent time.” It was a policy created early on that allowed employees to spend one fifth of their time on projects of their own choosing.

Gmail was one of the initiatives that came out of that process.

Google still allows employees to have 20 percent projects. But as a practical matter it’s been scaled back as the company grew. It’s limited and there are more hurdles to get approval.

A couple years ago while I was managing a team of Product Managers at Bloomberg I ran into one of the engineers from our group getting coffee. I asked them what they were working on.

The person described a project I didn’t recognize.

“It’s not on the board, it’s part of my 20 percent time,” the person said.

“What do you mean?” I asked.

“You know, how Google lets people spend 20 percent of their time on personal projects.”

I really wasn’t sure how to respond.

I wanted to say: “You don’t work at Google and Bloomberg doesn’t have 20 percent time.”

But I didn’t say anything. A cardinal rule among Product Managers is to try not to unnecessarily irritate the engineers.

I did have a few thoughts, however.

First, it’s obviously awesome to be an engineer.

Second, it’s ridiculous to have a board when there are projects that aren’t on the board.

Third, it’s fascinating how engineering has a culture that breeds expectations that extend across companies and even industries. It doesn’t work the same way for reporters or bankers or most professions. For example, a reporter might say “this is how they do it at the New York Times.” But it’s more of an observation than an expectation.

Fourth, companies should talk more about 20% time.

Google adopted the concept from 3M, which pioneered it in 1948. At various times, Atlassian, LinkedIn, Apple and the BBC have experimented with allowing individual projects.

3M engineer Arthur Fry used his side project time to create Post-It Notes. Both Google’s AdSense and Google News grew out of the company’s 20% time.

That said, I don’t think any major tech company is going to adopt 20% time these days. It’s too chaotic, too hard to manage and impossible to measure.

The issue isn’t so much the specific prescription, however, but more broadly how do big companies create a framework to encourage innovation.

The bigger a company gets the more the temptation to adopt a Six Sigma style mentality that focuses on process over product.

I’m curious what if any companies have 20% time or anything comparable.

Keep in mind, they may not know they have 20% time.

To find out, you may have to ask an engineer over coffee.