The spread of Coronavirus forced many companies to go remote. And some have already pledged to make the work style permanent.

Twitter (TWTR) said some employees who want to work from home permanently can, and Facebook (FB) CEO Mark Zuckerberg said as many as 50% of the company’s employees could be working remotely within the next five to 10 years. Google announced Monday that it would allow workers to remain remote until July 2021, but stopped short of committing to a permanent shift.

But sustaining a remote workforce over the long-term is easier said than done. We’ve seen companies have work-from-home policies only to eventually bring workers back to the office.

In 2013, Marissa Mayer, then-CEO of Yahoo, ended the company’s work-from-home option. And IBM called back some of its workers in 2017.

Part of the reason work-from-home policies don’t last is a change in project management, lack of employee trust or a decrease in productivity. But it doesn’t have to be that way.

Trying to have it both ways

Having a hybrid workforce with some employees in the office and others working from home can be difficult to manage. It might also put the remote workers at a disadvantage.

Workers at home don’t get daily face time with the boss, which can mean missing out on stretch assignments and career opportunities. Being off-site also eliminates any chance of random hallway run-ins, after-meeting chatter and other spontaneous situations that can provide valuable information.

But remote work policies don’t have to be an all-or-nothing situation.

The decision should be made at a team level, advised Debbie Lovich, managing director and senior partner at Boston Consulting Group. That means figuring out a schedule that works best for everyone and includes some days when everyone is in the office and then at home the rest of the time.

“Getting those team level norms is incredibly important,” she said.

If getting the whole team on the same schedule isn’t feasible, remote workers should still try to make regular appearances at the office.

“Ideally you should go into work once a week if you are going to be at home,” said Judith Olson, professor of informatics at the University of California Irvine.

The worst situation would be to have most employees in the office, and only one or a few remote workers, said Peter Cappelli, management professor at the Wharton Business School.

“When you are out of the office, people forget who you are and other people get access to information faster than you,” he said. “If you would be remote when no one else is, I wouldn’t want that job at all.”

Measuring results

Measuring productivity and evaluating workers’ performance can be an obstacle when companies switch to remote work. Managers need to set clear goals, priorities and measurables so everyone knows the expectations.

But not every task and role are quantitative. This is where trust comes in.

“Employee trust is a key hurdle,” said Jeanne Meister, founding partner at Future Workplace, a human resources advisory and research firm.

“Back when companies were pulling back [on remote work], they didn’t truly have employee trust. They didn’t train remote workers on successful strategies on being a remote worker.”

Successful remote programs require managers to trust that their team will get their work done when they say they will. And that old habit of equating presence with productivity is hard to break.

“Just because someone is sitting at a desk doesn’t mean they are being productive,” said Lovich.

Me vs. We

Office culture has become much more collaborative – it’s all about teamwork and combined efforts. And that doesn’t always translate well virtually.

“What we know for work that requires any collaboration, trying to do it virtually doesn’t seem to work very well,” said Cappelli, who sees very little chance that everyone is going to continue to work from home all the time after the pandemic.

And a recent study from the Boston Consulting Group found workers felt more productive on individual tasks than collaborative ones during the past few months of working from home.

The lynchpin to success: Managers

When it comes to the sustainability of working from home, it all comes down to the manager.

“Not everyone is good at learning how to manage remotely,” said Beth Kaufman, managing director at Boston Consulting Group.

Technology has also made it easier to communicate and collaborate, but managers have to step up and create a cohesive remote work style.

“You need supervisors who will run all the interference for you,” said Cappelli. That means figuring out who needs to connect on what projects, looping in the right people on reports and smoothing over any hard feelings when people feel left out or take an email the wrong way.

“The human dynamics don’t change because people are remote.”