NEW YORK (CNN/Money) - TV execs are supposed to be at war with TiVo, but given how the fall season is shaping up, viewers might need a digital video recorder just to find shows.

With all the tweaking going on with network lineups these days, the fall schedules are looking chaotic, industry analysts said. "I've never seen as many (schedule changes)," said Ed Martin, the programming editor for the Jack Myers Report, an industry newsletter. "We're having trouble keeping track."

For years, the networks have revamped schedules and experimented with off-season program launches in a bid to slow the ongoing exodus of viewers to cable, the Internet and video games. With networks facing one of their worst summer primetime seasons ever, the rejiggering is beginning to look desperate.

Too much shuffling could turn off viewers and advertisers alike, analysts said.

The biggest changes are from NBC and Fox and reflect the competitive pressures the two networks face.

With "Friends" and "Frasier" gone, NBC could lose either to CBS or Fox its longtime ratings lead among the young and middle-age adults coveted most by advertisers. NBC, ranked No. 2 overall heading into the fall season, knows it's vulnerable.

The GE (GE: up $0.04 to $32.83, Research, Estimates)-owned network will begin rolling out its fall premieres next week, two days after the end of the Athens Olympics and a full three weeks before the season's "official" launch on Sept. 20, as set by Nielson Media Research.

NBC's goal: keep viewers who tuned in during the Olympics around.

Ironically, Fox is revamping its schedule after a similar strategy bombed. Fox, controlled by News Corp. (NWS: up $0.32 to $31.32, Research, Estimates) and No. 3 in prime time last season, for years has looked to its October broadcasts of post-season Major League Baseball games to propel it into the November sweeps, when ratings help set ad rates at local stations.

It hasn't worked. "We've had a lot of failure launching new shows," acknowledged Preston Beckman,the executive vice president of strategic program planning at Fox. Shows Fox has launched during the traditional September premiers suffered because they couldn't build enough audience loyalty to carry them through an October full of nightly baseball.

In part to give shows more time to seduce viewers, Fox abandoned the traditional May-September season this spring and announced plans for year-round programming broken up into three time frames.

This summer the network unveiled three reality programs and four "scripted," or non-reality, shows. With three of the scripted programs due back in September, Beckman thinks the network may have created the viewer awareness needed to make it through the November battle for viewers.

But less than three months in, Fox's year-round strategy is looking dubious. Although the network plans to keep three of four summer shows on the air this fall, summer viewership leading up the Olympics had tumbled 15 percent from a year earlier, according to Nielsen Media.

By way of comparison, viewer levels were flat at ABC and up 4 percent at CBS. Before the Olympics brought a ratings surge to NBC, viewers were 12 percent down year-over-year at the network.

Sararuth Delice, a senior research analyst at media buying firm Carat USA, said Fox was smart to launch its prime time schedule early. "But If you don't have the programming to back it up, it doesn't do much for you," she said. Too many scheduling changes and show launches risk confusing viewers and alienating advertisers, she said.

"Viewers don't have a chance to get attached to a program," she said. "Advertisers generally prefer more stability."

Beckman, the Fox executive, acknowledged there have been short-term problems, but insisted that Fox is positioning itself well for the long-term.

"We would prefer stability," he said. "That's the long-term goal here and it's true of any network."

This year, as the juggling has become more frenetic, rival executives are sparring more openly than ever before.

"Network presidents love to take shots at each other, but they've never been so vocal as they were this summer," said Martin of Jack Myers Report.

Among the highlights: NBC Universal Television President Jeffrey Zucker in July accused Fox of stealing other networks' programming, calling it unfair play that's "just bad for the business." The producers of one upcoming NBC reality show about boxers, "The Contender," have hauled Fox into court in the hopes of blocking its plans to air a rival program, "The Next Great Champ."

According to Jeffrey Bader, ABC's executive vice president for prime time shows, "The spread between first and last (in ratings) has gotten smaller and smaller. There's little wiggle room, and anyone can end up being on top."

Fox is ready for more fireworks. "It's going to be an extremely competitive season," said Beckman.