The late Walt Dette from Roscoe, NY., once said: 
"I have invented such flies as the Coffin and Delaware Adams. 
But I try to stay away from originating patterns, because I feel
  the market is flooded with new flies and many of them are very similar. 
You can invent a new pattern every day or week, but it will not 
necessarily be better at catching fish. I have tried to talk to the fish over 
many years about what they think, but have not gotten an answer yet. 
One person will say a certain flyis the greatest, the next will say it 
is the poorest.You could live on a stream and find out something 
new all the time.There is a lot to learn".

"COFFIN FLY" Courtesy: Walt Dette.