Researchers found 51% of adults admitted to sitting down to at least four hours of shows, aired again by broadcasters, that they had already seen before.
Half of adult viewers spend around 16 months of their lifetime watching repeats, researchers said. The average adult spends three-and-a-half hours every day watching TV, and according to the survey for movie and TV streaming service blinkbox, nine years across an adult lifetime.
Some 53% of Britons have watched the same shows so often that "they can remember most of the words and say them in time with the actors".
The survey found 51% of adults consume four meals every week while watching TV and 54% of those questioned said that they watch TV while online. A total of 2000 adults were quizzed by One Poll.