NEW YORK (AP) — NBC is giving the equivalent of broadcast timeshares to 'Heroes', 'Chuck' and some of its six new series to keep airing original fare in a schedule where the chief constant is Jay Leno.

The network is building prime time and its hopes to escape fourth place around Leno and the boldest experiment in network television in some time. His comedy show will begin airing at 10 p.m. five nights a week in the fall.

With the workaholic Leno providing new material year-round, NBC felt the need to surround him with as few repeats as possible, said Ben Silverman, co-chairman of NBC Entertainment and Universal Movie Studios.

"We'll have more original programming this year than ever before," he said.

The oddball secret agent series 'Chuck' was on the bubble until saved by an enthusiastic campaign by fans and a sponsorship deal with Subway. It will air 9 p.m. Mondays after NBC televises the Winter Olympics, while 'Heroes' occupies that time slot in the fall. Similarly, NBC will air the new series about paramedics in San Francisco, 'Trauma', at 10 p.m. Mondays next fall. The new science fiction 'Day One' will replace it in the spring.

The idea of limited-run series has seeped into broadcast TV from cable, with viewers showing little patience anymore for reruns.

NBC will start its new Chevy Chase series 'Community' Thursdays after 'The Office' in the fall, with the Emmy-winning '30 Rock' coming on the air about a month late due in part to movie commitments this summer by Tina Fey and Alec Baldwin.

The network is opening Thursdays with a handful of 'Weekend Update' specials from 'Saturday Night Live', followed by the Amy Poehler mockumentary 'Parks and Recreation'. 'My Name is Earl' was shown the door, along with 'Medium' and the game show 'Deal or No Deal'.

The fall schedule will include the return of 'Law & Order' for its 20th season, which will tie it with 'Gunsmoke' as TV's longest-running prime-time drama.

NBC had previously announced that sister show 'Law & Order: Special Victims Unit' will return in the fall, although contract negotiations with stars Mariska Hargitay and Christopher Meloni had yet to be resolved.

Another fall debut is 'Parenthood', produced by Ron Howard and based on the 1989 movie he directed.

The family drama, starring Peter Krause, Maura Tierney and Craig T. Nelson, will air 9 p.m. Wednesdays, with new hospital drama "Mercy" set to claim the slot midseason.