I think this is the best way to think about it: Ask yourself, if some fact or functionality changes, in how many places would the code have to change? If it's

I think this is the best way to think about it: Ask yourself, if some fact or functionality changes, in how many places would the code have to change? If it's more than 1, you have a design problem. Of course, the solution does not at all have to be about DRYing.