Rules can be helpful (when learning or when you're stuck) and they can get in the way (make you boring or predictable)*.
*I realize boring is a good trait sometimes. but boring can also be... boring.
The thing is, the "rules" are rarely so precise as to make anything fully predictable. What distinguishes a good outfit from a bad one is just as likely to be a matter of execution within the rule as whether the rules were followed.