We subscribe to the following high-level theories in our Sass code:
Keeping functional Sass separate from presentational Sass is important in order to maintain readability, search-ability and scaleability of your code. Patterns like placing mixins in the same file as presentational Sass leads to overly complex files to scan and opportunities for accidental pollution of your processed CSS. Source: http://gist.io/4436524
"Sass is not a replacement for CSS, it’s more like having a CSS assistant who will help you write your code. So when you’re ready to really put it to work I recommend occasional sanity checks on the resulting CSS to see if this “assistant” has created too much repeated code or if the selectors are getting too complicated. Refactoring your Sass will help keep your code clean and you’ll start learning how you can make the best use of it."