If you have a bronzer that would be the perfect shade as an eyeshadow then use it as an eyeshadow, if your contour brush would the perfect foundation brush for your face then do it! Don't ever feel restricted by what you think you should do and don't be afraid to get creative. At the end of the day if it looks awful you can always take it off and start again.
The same goes for rules you may have heard for example about how to highlight and contour. Everybody's face is different and if it works for you then go for it!
Don't be afraid ladies, try something new!
Take care ♥