The original, "Tennerfest", was a good idea. It got chefs/establishments into some sort of competition to see who could produce the best menu for a ,"Tenner".
Once it became, "£10, £12.50, £15, £17.50, FEST". It lost its appeal.
No point in going to a , "Tennerfest", establishment, if you are going to end up paying what you would be paying in any eatery anyway.
The original , "Tennerfest", encouraged folk to eat out during the week, (When you couldn,t be arsed washing-up etc), but once the, "Tennerfest", bills started to match the, "Night Out", it was always going to take a dive.