Not Offering Flex Time? You're in Trouble. Here are a few of the key issues companies face when considering moving to more flex time and how to execute it in a way that keeps employees happy while emphasizing productivity.

Everyone likes perks, and today, businesses are waking up to that fact. Many are offering "in-house" bonuses like fully stocked fridges, free gym passes and employee relaxation spaces with Ping Pong or Foosball tables.

And while these benefits bring a sort of "laid back" vibe, this type of workplace environment isn't for every business. But there is one perk that virtually any company -- in any industry—would be wise to explore: Flex time.

Flex time, allowing your employees to work flexible hours instead of the traditional 9-to-5 schedule, continues to increase in importance for workers across the age, gender, ethnic and culture spectrum. Millennials, in particular, are huge fans. In fact, according to a survey by FlexJobs, "85 percent of millennials would prefer to telecommute full-time and seek flexible work options for more work-life balance." Fifty-four percent prefer a flexible or alternative work schedule, and 97 percent say that a job with flexibility would positively impact their overall quality of life. Just as significant is that other surveys, like this one from CTrip.com, suggest that, while traditional offices can be useful as a creative and social outlet, employees are often more productive when they have the ability to focus at home.

Related: Why Summer Fridays and Flexible Hours Are a Must

Here are a few of the key issues companies face when considering moving to more flex time and how to execute it in a way that keeps employees happy while emphasizing productivity.

Instead of measuring time spent, measure goals met

There are more than a few Dilbert and The Oatmeal comics out there that skewer the absurd notion that "time spent" is somehow more valuable than the overall quality of the final deliverable.

In other words, "time spent" vs. "goals met" still requires a significant shift in thinking for many managers. One way to begin changing your thinking is move to a SMART goals methodology and measure progress toward meeting established goals. SMART goals are specific, measurable, action-oriented, reasonable, timely with written statements outlining their specifics.

Flexibility doesn't mean anything unless it's exercised

One current trend that's beginning to get more attention is "unlimited paid time off." While it's gathered plenty of steam, it has also faced skepticism from many HR professionals. They note that, while the concept of unlimited PTO sounds great initially, it's a stretch to imagine employees taking full advantage of this trend—when most don't even manage to take the yearly time off currently on offer.

And that raises a good point. Flexibility, like most concepts in a workplace, has to be considered well within the context of your company's current culture. For some organizations that means working night and day to deliver a massive project and then taking a couple of weeks off, for others, it may mean a parent being encouraged to take a guilt-free few days off when family emergencies pop up.

Related: How to Create a Formalized Flexible Work Program for Your Company

Perhaps the most important consideration, however, is this one: your leadership team needs to model whatever flex time structure you adopt for the rest of the company. If senior employees continue to burn the midnight oil or drag themselves to work while flu-ridden, that communicates to the rest of your staff that to maintain job security, you had better make yourself always available. And if those are the subtle messages being communicated at your company, that needs to be addressed.

Provide flexibility on the little things, so the big things get done

Of course, how a business operates and the level of importance placed on one initiative over another will vary depending on the vertical and the overall business model.

Problems arise when managers fail to grasp this, and instead micromanage the smallest of assignments, demanding they be completed in the same manner as much bigger initiatives. By allowing even the most junior of employees to have ownership of tasks, and to define how, when and where they get these smaller things done, you will end up with motivated team members who feel trusted and will deliver much better work.

Trust and motivation are invaluable when it comes to job satisfaction and executing on larger priorities. Hiccups in either of those two areas can cost companies a lot.

Regardless of how you structure corporate flex time, keep in mind that it's a collaborative process. Each company's ecosystem is likely to be unique. Giving employees a say in how they can develop their careers and create work-life balance will result in a workplace the best candidates are eager to join, and a dynamic organization seeing year-over-year growth.

Related: Your Workers Want Work Flexibility But Companies Benefit Most