It's a misunderstanding of DRY that leads to most of the nonsense. The original formulation, in the Pragmatic Programmer, was: "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system."
This very much requires "understanding underlying patterns" - what knowledge does your program encode? How can that be broken apart and localized?
Obsession with repetition of surface syntax isn't DRY and isn't useful. It goes wrong in two ways. First, knowledge can be repeated without repetition of syntax. If I'm telling my HTML "there is a button here", and my CSS "there is a button here", and my javascript "there is a button here", those three statements may look nothing alike but that's not DRY.
Second, if two pieces of code happen to look identical, but each is the way they are for different reasons, they encode different pieces of knowledge and collapsing them is not DRYer. As I've said before, in that case you're not improving your code, you're compressing it. I like to call that kind of overzealous misapplication of DRY "Huffman Coding".
This very much requires "understanding underlying patterns" - what knowledge does your program encode? How can that be broken apart and localized?
Obsession with repetition of surface syntax isn't DRY and isn't useful. It goes wrong in two ways. First, knowledge can be repeated without repetition of syntax. If I'm telling my HTML "there is a button here", and my CSS "there is a button here", and my javascript "there is a button here", those three statements may look nothing alike but that's not DRY.
Second, if two pieces of code happen to look identical, but each is the way they are for different reasons, they encode different pieces of knowledge and collapsing them is not DRYer. As I've said before, in that case you're not improving your code, you're compressing it. I like to call that kind of overzealous misapplication of DRY "Huffman Coding".