Carrie Underwood walked off the American Idol set and straight into a Nashville studio; Kellie Pickler and Kristy Lee Cook followed. Miranda Lambert came from Nashville Star, Julianne Hough from Dancing With the Stars. Crossover act Jessica Simpson had Newlyweds: Nick & Jessica.

Country has plenty of blondes with no TV shows in their past — Taylor Swift, Sugarland's Jennifer Nettles, former Trick Pony lead singer Heidi Newfield — but TV exposure often gives artists a head start on acts coming up through traditional avenues.

"The great thing with that is instant recognizability," says Marci Braun, music director at Chicago country station WUSN-FM. "Right away, you know who Kristy Lee Cook is."

Artists with built-in audiences also don't have to rely as heavily on radio, which historically has been the primary way of breaking new acts.

"They have support among young girls who watch a lot of television, so they do sell in downloads," says radio consultant Jaye Albright.

Underwood has far outperformed the rest. She's had seven No. 1 hits, with another, Just a Dream, moving up the top 10. Lambert, Pickler, Hough, Simpson and Cook have yet to find their first chart-toppers.

"The success seems to be diminishing with each one," says David Ross, publisher of trade magazine Music Row. But consumers don't look at artists "as being the same thing they're ordering over and over."

Still, casual fans may have trouble keeping them straight. And there are indications that a little bit of these singers goes a long way with listeners. "We're seeing bad research on songs by some of these females," Albright says. "Not dislike, it's 'I'm tired of it.' "

Labels may be dipping too far into the talent pool looking for the next Underwood, who won Idol in 2005: Cook finished seventh last season. Several country stations, including KKGO in L.A., are taking a wait-and-see approach to Cook's 15 Minutes of Shame, currently No. 36 on USA TODAY's country airplay chart.

"I'm skeptical about the runner-ups until I see a proven single," says KKGO program director Tonya Campos.