, my friend and I solve Sudoku's using 7 logic processes. I learnt how to do them using the times ones but I've discovered that the times ones (even fiendish) are not the hardest available and only use max 5 of our 7 stages of logic.Though the early daily telegraph puzzles may have been inferior their latest 'diabolical' are very hard, all solvable by logic not T+E, have 1 unique solution and use all 7 of the logic stages we have worked out. They looked pretty symmetrical too.
So I for one am going to stop slagging off the DT until the Times start publishing puzzles that use the more difficult logic techniques that are harder than DT
Other people may have worded them differently too. If you can do feindish you've got 5. Try some of the harder ones and you should pick up 6 and 7. I didn't invent them so I don't want to take the credit