It’s one of theme parks’ biggest challenges: finding ways to ease the pain of waiting in line.

Disney’s Hollywood Studios tried something unusual for a few days recently, when it required FastPass reservations for anyone boarding the Toy Story Midway Mania ride.

Disney said it doesn’t have any immediate plans for an appointment-only ride, but the test was designed to gauge whether more guests were able to ride Toy Story using FastPass only and to see how visitors reacted.

Amusement parks have plenty of motivation to lessen waits, or at least make them less boring, analysts say. Guests leave happier — and are more likely to return. Shorter lines at popular rides mean tourists have more time to visit secondary attractions.

And time not spent in line means more cash at the registers in a park’s shops and restaurants.

“People standing in lines aren’t spending money,” said Duncan Dickson, a former Disney executive who now teaches at the University of Central Florida’s Rosen College of Hospitality Management.

Jim MacPhee, Walt Disney Parks and Resorts senior vice president, said in an emailed statement that Disney is “laser focused on enhancing the experience of our guests, and tests in the parks are one of many ways we gain insights” to help do that.

The FastPass experiment isn’t the industry’s first try at fighting lines.

A few years ago, Disney created an underground center in which employees monitor crowds via computer and video camera, then decide which congestion-fighting weapons to deploy. A ride might launch more vehicles, for example, or a restaurant could open more registers.

Early access for hotel guests also helps. Visitors who stay on Disney and Universal Orlando property get to enjoy the parks exclusively for an hour or two a day — which gives them more incentive to hang out at their hotels in the afternoon.

The parks’ arsenal of crowd-control tactics also includes distractions, which have grown increasingly elaborate. At Disney World’s renovated Fantasyland, for example, kids frolic in an indoor playground until buzzers alert their families it’s time to board the Dumbo ride. Disney also added a second Dumbo carousel to handle more riders.

A big part of the strategy, however, is allowing a certain number of people to skip lines altogether.

Disney has taken a different approach to this than its primary competitor here, Universal Orlando. Universal visitors can pay for Express Passes or get them by staying in the resort’s luxury hotels. They start at $35 for a basic one-park deal, but unlimited line-skipping for both parks can reach up to $150 on peak days.

Universal’s program “was designed based on feedback from our guests and a great deal of research from our team,” spokeswoman Alyson Lundell said in an email. “It helps guests experience everything our destination has to offer at their own pace during their visit.”

At Disney World, the emphasis is on good planning. Anyone can request up to three free FastPasses at a time for select rides. They are assigned one-hour windows during which they can walk into the ride in almost no time.

Disney has shunned the idea of charging for the passes because “they felt it would disenfranchise a group that couldn’t afford to upgrade,” Dickson said. “They just felt that within their culture, it just didn’t fit.”

Instead, Disney has tried to encourage more widespread use of the passes through its MyMagic+ billion-dollar technology project. Guests can now reserve rides and shows up to two months before their visits. And the number of attractions eligible for FastPasses has doubled.

Seventy-five percent of Walt Disney World guests use FastPasses now, compared with fewer than half who did so when they could only reserve them in the park.

Because so many people already use FastPasses, many didn’t mind the brief change at Toy Story Midway Mania. The 3-D ride is one of Hollywood Studios’ most popular attractions and has a reputation for painfully long waits of more than an hour.

On one of the test days, its characteristic snaking lines were gone. Guests booked FastPasses that day and walked on in two to three minutes.

For some, though, change brought confusion. Jennifer Franch of Dublin, Ohio, snagged a Toy Story reservation on her smartphone but lost FastPasses for two shows in the process.

Lisa Hulman of Huntsville, Ala., had trouble reserving a time for her family online. Even after getting one with the help of a Disney employee with a tablet, she remained frazzled.

“I don’t like it,” she said. “I was about in tears.”

No matter how Disney or its competitors tinker with their crowd-management systems, don’t expect to see a lineless theme park anytime soon.

Ushering guests through too many attractions too quickly, and a new set of problems is created. Visitors might get bored if they see everything too fast. And during busy times, crowds could end up clogging stores, restaurants and avenues instead of queues.

“The flow within a park assumes a certain number of people will be standing in line, more so during peak periods than nonpeak periods,” said Joni Newkirk, a former senior vice president at Disney who now runs a consulting firm called Integrated Insight. “You take them out of line, and where do they go?”