Sainsbury deli buyer Richard Pitcher insists customer service is crucial: "We are working to draw people to the counter by making pricing simple and providing more information about products. Keeping queues down by investing in colleague hours is also important."
However, he adds that tried and tested ways of driving sales are also important: "We support the range through sampling, instore promotions and advertising."
Pitcher says having a large variety of strong products helps, too: "We are constantly looking to improve the range through innovative, good quality new products which appeal to our customers."
Tesco links the slight overall decline in deli sales to customer preference for convenience and speed. It says the trend is reflected in sales of pre-packed food versus over-the-counter equivalents. Shoppers often don't want to bother with ordering over the counter.
Co-operative Group category manager of chilled foods Mike Owen agrees: "Deli sales mirror pre-packed in that cheeses and cooked meats - Cheddars and hams - are the bestselling lines. However, deli sales are only a fraction of pre-packed sales."
The society took radical action in redesigning the whole deli area to draw people back. Owen says: "The fixture has been modernised with new tickets, decking, new uniforms for staff, new point of sale and stronger promotions."
Tesco's solution has been to introduce a grab and go' format in 30 stores over the last year, which it continues to roll out.
But Bob Farrand, national director of The Guild of Fine Food Retailers, says new formats can sometimes be counterproductive and insists the multiples would benefit more from better training.
"Multiples claim customers don't want to queue, so they create a hybrid counter where everything is cut into portions and customers can help themselves," he says. "This defeats the object of a deli counter and restricts experimentation and expansion. If they invested in more staff and trained them, customers would be served more quickly."
He says a well-trained, experienced buyer will pull in a wide range of products which will drive sales. "Most buyers have no knowledge of the cheese business. Look at the range in Waitrose and compare it with Tesco, Sainsbury or Asda. Waitrose's cheese buyer trained at Harrods and ran a deli - he knows his stuff."
Better training would also help staff give reasons for the premium pricing that often comes with speciality food, says Farrand. "Unless there are staff on hand capable of explaining the differences between mainstream and regional and justifying the cost benefits, customers buy the cheaper food and regional specialities end up as half-price offers in dump bins."
He says Waitrose has got it right: "Only Waitrose has tackled the problem head on and succeeded. Its staff are released from branch to take the full UK Cheese Guild training course, including the exam and a half-day instore assessment."
Waitrose says good visual presentation is important but outstanding customer service is the first priority. It has introduced hand carving as a strong feature of its deli counter in the last year. This allows shoppers to control portion size and weight.
Meanwhile, it reports deli sales rising steadily.