In 2015, the team behind the bright, Spanish-inflected Lake View café MFK, well loved for its seafood a la plancha, undertook an experiment: For one year, they’d try brunch service.

It seemed like a smart call. Brunch is booming, and it’s not just the omelet factories strategically located in millennial-heavy neighborhoods that are cashing in. Places vying for critical attention—often ones geared toward serious dinner service—are making brunch a priority: Of the 159 recommended restaurants in Chicago’s dining listings, 58 of them offer a weekend brunch. Eight of the 15 entries on this year’s list of best new restaurants, from fancy-French the Blanchard to mom-and-pop Ixcateco Grill, are open for brunch, too.

MFK’s co-owner Scott Worsham framed his decision succinctly: “You want to get every dollar you can out of your business.”

Except the math doesn’t always work out, especially for restaurants with tight margins and small staffs, like MFK. First, you’ve got to pay employees to come in—frequently staff who are exhausted from staying late at the restaurant the night before—to prep and cook for brunch and to stay on for dinner, which makes for a packed kitchen and hastens burnout. “But it’s a fine line,” Worsham says. “It’s like being open on a holiday—you’ve gotta pay rent anyway, but what do you do about quality of life for your team?”

You’ve also got to do quite a bit of promotion—press releases, social media outreach—to get the word out about an added meal. “We sent out two more press releases and got a little hit with each one,” Worsham says, but the uptick wasn’t sustainable. In May 2016, despite enthusiastic feedback from customers like myself—I’m still mooning over my toast topped with silken scrambled eggs and delicate flaked trout—MFK’s brunch got scrapped.

Other aspirants have met similar fates. Logan Square’s Table, Donkey and Stick ended its experiment after less than a year. Osteria Langhe stopped in January 2015, after just seven months, in part because of stiff competition from Logan Square institutions like Lula Cafe and Bang Bang Pie & Biscuits. Langhe chef-owner Cameron Grant says that to make brunch profitable, he needed at least 100 patrons per service, but most weekends saw roughly about 50 to 60—perhaps a sign that, even in boom times, there’s only so much brunch love to go around.

“You need people to show up and see that it’s a scene,” says Grant. “If you don’t have that, it doesn’t work.”

As for my beloved trout toast at MFK, it’s still around. It’s available as a Sunday special—after noon.