Network and cable execs have a tough new competitor to square off against in primetime: themselves.

In the past year, the volume of DVR playback viewing that occurs during primetime hours has reached the point where the DVR now ranks as the No. 1 network. The ratings generated by viewers opting to watch time-shifted programs — from across the television dial — are equivalent to the averages of the Big Four networks combined.

Alan Wurtzel, president of research and media development for NBCUniversal, offered this staggering statistic in a recent presentation on the state of TV viewing. But what is most unnerving for traditional TV executives is the accelerated pace of change during the past seven years, such as how quickly tablets have been embraced by consumers and become a significant TV viewing platform.

The “mainstreaming” of time-shifting options such as the DVR, VOD and streaming services with older viewers is driving the growth in multi-platform viewing. Younger viewers were quicker to embrace new options for watching television on their own timetables, but they now have plenty of company.

“This behavior is no longer about a bunch of 25-year-olds who wear black and live in Williamsburg,” Wurtzel says. “It affects everybody across the country.”

All this time-shifting means network programmers have to adapt to two big challenges. They need to work harder to give viewers a reason to tune in to a program on the night it airs, and they need to understand the dynamics that drive time-shifted viewing patterns. With the explosion in the volume of original content offered by TV and digital outlets, the most avid TV viewers are no longer just using DVRs and other devices to catch up on shows. They’re using on-demand options as tools to create their own primetime lineups.

“We talk about (how) the consumer wants control,” Wurtzel says. “But the fact of the matter is what’s going on now has really gone way beyond control. It really is the consumer as curator. And by ‘curation,’ I mean these (viewers) are customizing what they get and how they get it.”

The broadcast networks have the additional problem of fighting the perception that viewership is steadily declining. There is activity in the streaming arena to offset, if not reverse, the declines for some programs, but the numbers for streaming haven’t been as readily available because of technical hurdles involved for Nielsen’s measurement systems.

Meanwhile, Nielsen’s linear TV numbers show a big drop in overall television usage among key demos between 2008-13, such as a 17% decline for the adults 18-24 demo and 15% drop for adults 25-54. This was a red flag for network research execs because the “persons using television,” or PUT level numbers, “move glacially,” Wurtzel said. Such a big drop in a short period did not compute — until they realized how much activity was happening beyond the living room screen.

Wurtzel offered estimates for the size of streaming as a component of overall viewership for three NBC shows — “The Blacklist” (17%), “Parenthood” (21%) and “Parks and Recreation” (37%) — none of which is factored into Nielsen’s tallies at present. The numbers were derived from studying the number of streams NBC delivered for the show in a given time frame. He acknowledged that it took an “enormous” amount of work and involved some educated guesses.

Nielsen is under pressure from its TV and advertising clients to vastly improve its measurement systems. This fall, it is set to begin measuring viewing done via tablets and smartphones as part of its national sample — which means moving a step closer to the omnibus rating that the networks desperately want. Streaming viewing done via laptop and PCs can be rolled in to that number as well if the program carries the same national advertising load as on the linear telecast. But that’s been a constraint for some networks that want to experiment with different ad models in the digital realm.

As for VOD, some 40% of free VOD usage is replays of broadcast primetime series. More than half of U.S. TV households have VOD available to them via cable, and three-quarters of those use VOD a least once a week. The “sweet spot” of the demo for DVR usage is adults between 25 and 50.

In the 2008-09 season, the year after Nielsen introduced DVR ratings measuring the seven-day period following a program’s premiere, 83% of program viewing was done live, while 8% was done on the same day and 7% within the first three days. Five years later, live viewing has dropped 27% and live same day viewing spiked 75%. Viewing within three days has increased 20%.

“This is a phenomenon that is just taking off. In other words, it’s just something we can’t ignore anymore,” he said. “So whether it’s a huge amount or somewhat less, it’s still a phenomenon that’s only going to grow as the mainstreaming continues and as the proliferation of these devices continues and as the behavior as a result changes.”

This is the biggest challenge for scheduling, especially with the emphasis on live events and limited series designed to drive can’t-miss tune-in, social media buzz and second-screen activity.

“The linear schedule is hugely important … but we better realize that there are changes taking place that we have to take into account,” Wurtzel said. “We just can’t fall back on the idea that ‘We’ll show it to them, and they’ll come.’”

In a world of on-demand instant gratification, it’s hard to train executives and journalists to allow for the time needed to collate all the data that dribbles in from disparate sources about program viewership. It doesn’t help that it takes 20 days for Nielsen to process even the live plus seven ratings, Wurtzel noted. But in the new world of TV watching, patience is a virtue.

“Making a decision about a program based upon the next day’s rating is kind of like deciding if you want to marry someone after a seven-minute speed dating session,” Wurtzel said.