As has become the norm, TV networks are continuing to bolster their commercial loads in attempt to stave off declining ad revenue.

AMC Networks increased its ad load by 10% in the second quarter, the most of any other network group, followed by Viacom, whose commercials were up 7%, and A&E Networks, which was up 5%, according to a report from Sanford C. Bernstein.

"The continued ad stuffing is an obvious and unsustainable (some would say 'desperate') action by the networks to prop up ad revenue in the face of declining audiences," wrote Todd Juenger, analyst, Sanford C. Bernstein. "Not only can this not be sustained going forward, it further contributes to the audience declines making SVOD [streaming video on demand] that much more preferable for viewers made numb by the absurd amount of ads (as well as decreasing the efficacy of the advertising that is still seen)."

In fact, all cable network groups, excluding Fox, increased their aggregate ad loads year-over-year, according to the report, which does not measure news and sports programming.

Viacom and A&E continue to up their ad loads as they experience significant declines in commercial ratings. Viacom's C3 ratings among adults 18 to 49 were down 16% and A&E was off 18%.

While AMC Networks only saw a 3% bump in its C3 ratings for the demo during the second quarter, it increased its ad load more than any of its peers.

"Such a dramatic increase in ad load, as indicated by our data, would not be a total surprise. AMC's original programming ratings have underperformed expectations…perhaps forcing the network to make up the difference by increasing the size of its inventory elsewhere," Ms. Juenger wrote.

Kids' networks led the way in ad stuffing, with Nickelodeon increasing its commercials by 6% and TeenNick and NickToons up double digits. Cartoon Network raised its commercial time by 4%.

Overall, C3 ratings in prime time among adults 18-to-49 declined about 9% during the second quarter.