But on Monday, Verizon Communications surprised the industry by announcing it had added the faster approach in 461 markets covering almost the entire country. That should allow many Verizon customers to spend less time waiting for a new music track or video to download onto their phones.

Known as carrier aggregation, or LTE-Advanced, the technology lets one phone receive data over several wireless channels simultaneously, instead of just one. It requires that carriers update software on cell tower base stations and have enough available spectrum to let some phones use more. Verizon is considered by analysts to have less unused spectrum than its rivals.

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AT&T (T), the second-largest carrier, was talking about how it rolled out carrier aggregation in Chicago a few years ago, but hasn’t made much noise since. At this point, AT&T’s LTE-Advanced offering covers territory where the majority of people in its LTE network live, a spokesman said.

Third-largest carrier T-Mobile (TMUS) said at the end of last year that it was using carrier aggregation for what it called Extended Range LTE in 300 markets. And Sprint (S), the fourth-ranked carrier, said in April that it offered the technology, under its LTE Plus moniker, in 191 markets, including major cities like New York, Chicago, and Atlanta. On Monday, Sprint reported on the results of its latest carrier aggregation testing, noting it now offered the technology in 237 markets.

Verizon’s leap forward could add to its reputation for having a quality network. And the added speed boost could be welcome at a time when rivals have been closing the gap. Any speed increase also would be welcomed by customers, who are facing a long wait before the next generation of wireless technology beyond LTE, known as 5G, is ready.

But just how much difference LTE-Advanced from any carrier makes in the real world is open to some questions.

Only customers with compatible phones can benefit, though most popular models from the last few years from Apple, Samsung, and others will work with carrier aggregation, according to Verizon. And the amount of extra spectrum for each carrier that’s available for combining differs from market to market, even block to block in some cases.

Verizon, for example, says its faster speeds will only kick in like a turbocharger on a car engine, when a customer is downloading a lot of data at once. Otherwise, customers “will continue to enjoy typical download speeds” of 5 to 12 Megabits per second, or Mbps, Verizon (VZ) says. And while the maximum possible speed of LTE-Advanced is 225 Mbps or more, even when carrier aggregation kicks in, customers’ maximum download speeds will increase generally by only 50% over regular LTE, Verizon says.

Some analysts also aren’t sure just how broad the LTE-Advanced coverage is in each market where it has been deployed.

“It would be great to know the amount of coverage that define these launches,” asks BTIG Research analyst Walt Piecyk. “It’s nice to have super fast speeds at random cell sites but if the consumer is handed off to less spectrum intensive LTE or 3G as they walk down the street, the consumer could be disappointed.”