For the second time in a week, there’s word that TV commercial clutter, the bane of media people, has finally stopped growing.

And broadcast clutter has actually declined slightly compared with last year, according to a new study released this morning by Magna Global USA, the media buying giant.

Non-program time on the Big Four networks, which includes commercials, public service announcements and network promotion time, fell an average 8 seconds, to 16 minutes and 29 seconds, compared with last year for dramatic series and by 5 seconds, to 8:24, for comedies.

The previous year, Magna found a 22 second decline for dramas but 7 second rise for comedies.

The study also finds that NBC was the only network to show year-to-year increases in the length of non-program time for both sitcoms and dramas. In the latter category, the networks slashed 30 seconds from their average commercial pod time two years ago.

The report comes days after MindShare released its annual commercial clutter study, which found that ad clutter was even to the previous year. That study included broadcast and cable, while Magna looked at just broadcast.

Advertisers have railed against rising commercial clutter for years, saying that it makes it harder for their messages to stand out. Though media people caution that 16 minutes per hour is still a huge chunk of time, the decline is seen as promising. It indicates that networks may be finally heeding advertisers’ calls for less clutter, or perhaps realizing that there’s simply not much more room for clutter.

The study did find an increase in national commercial time, which is in part being offset by fewer network promotions than in the past.

“Since most people are limited to just looking at national commercials (all that Nielsen provides), it seems to many that overall non-program time has gone up,” writes Steve Sternberg, author of the report and Magna’s executive vice president of audience analysis.

“Since we taped and logged in every program in our studies manually, and lined up our log seconds with Nielsen’s NPower-reported minutes, we were able to get data for the full commercial pod—including promos (which Nielsen doesn’t measure properly), and local commercials (which Nielsen includes as program time).”

The biggest rise in national commercial minutes time for dramas came on ABC and NBC, up 55 seconds and 22 seconds, respectively, over the past two years.

Overall, ABC had the most non-program minutes for dramas at 17:17, followed by NBC at 16:51, Fox at 16:01 and CBS at 15:56.

While national commercial time was up for dramas, every category was relatively stable for sitcoms.

“The commercial pod data for comedies was more stable than for dramas, with little change in the overall amount of non-commercial time, national commercials, local commercials, or network promos,” Sternberg writes.

For comedies, NBC led with 8:40 non-program minutes, followed by Fox at 8:37, ABC at 8:19 and CBS at 7:47.

The Magna study was based on analyzing one episode per month from November 2006 to February 2007 for 60 primetime programs.

The networks have been exploring alternative ways to deliver advertisers’ messages in addition to the traditional commercial. The CW used content wraps, which integrate entertainment and ad time in a commercial pod, and ABC is experimenting with so-called pop-up messages that appear within a program.

This is in part a reaction to advertiser concern that their ads are being skipped by viewers using digital video recorders.

There may be a better gauge on whether any of these ideas will work in the long term starting next month, when Nielsen begins releasing its long-delayed commercial pod ratings.