When you read through the code you should be able to understand what's going on by just looking at it. If you need to look up the [[function signature]] or variable definition - it means that they are not clear enough.
[[functions should have a small number of arguments]] - because for the function with the large number of arguments it's hard to understand the full consequence of calling it and how the arguments impact the function behaviour.
Named arguments do help to make this clearer to some degree though.