Tesco TV has proved a rare misfire for the retailing giant, which boasted upon launch that it would bring advertisers an audience of a similar size to Coronation Street's.
"I think, having walked a few stores recently, we have not seen the level of advertising they would have expected to see on those screens," said Simon Hathaway, the managing director of Saatchi & Saatchi X, the retail division of the advertising agency.
Tesco, Asda and Sainsbury's have all introduced in-store TV as a way of helping suppliers persuade shoppers to buy their products, while at the same time handing a small revenue boost to the supermarket.
But so far it appears it is proving more difficult to achieve than at first sight.
Industry experts say the jury is definitely still out.
"It's had more pilots than British Airways," said Guy Vaughan, a director of Retail Marketing Services, the research company and consultancy working with Asda.
"There's a lot of experimentation at the moment and I think that the industry is struggling to find a measurable framework which we are about to overcome."
By August RMS would have a means of showing clients a measurable return on investment, he said.
But the advertising industry remains disappointed with the concept, with assessments ranging from "grossly unsuccessful" to "incredibly expensive".
One informed estimate put the cost of each TV screen at £500, meaning that Tesco has spent £2.75m on installation alone, although the chain is known to have done a bulk deal on the screens.
However, there are some easy fixes - such as where the screens are positioned.
"The general feeling across the industry is that Tesco have got it wrong in their location [of television screens] on the power aisle [the central aisle that cuts across the store]," said Saatchi's Mr Hathaway.
"They are well above head height and don't interrupt line of sight. I'm interested to see the Asda test result. They are testing two models and at the Wembley store you cannot walk into an aisle and not see it," he added.
Asda is trialling screen in stores in York and in Wembley and a trial with five partners including Coke, Nestlé, Reckitt Benckiser and Unilever produced a sales rise of 11%, the supermarket said.
David Martin, the corporate brand manager for the Asda media centre, said it had not decided the future of the scheme. "We are actively looking at different scenarios at the moment," he said.
Asda could offer 12 million customers a week.
"It's a big volume of customers, [they are] in the mood for purchasing," he said. Rivals expect that the store will roll out more screens.
The consumer goods giant Procter & Gamble echoes industry caution about the scheme.
"Our position on this is, we have been doing some work on supermarket TV with one of the chains at a pretty low level," said Bernard Balderston, the associate director of UK media at the company. "We have tried to evaluate if it had any benefit and are waiting for the results at the present time," he said.
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