Redox for covalently bonded species?

Redox #'s are used simply as a method to have a handle on where electrons are moving. It is just something people invented to make their understanding of certain reactions easier.

 

What gives you the impression that there is no change in oxidation state when covalent species react? In fact, I'd venture that most changes in oxidation state are seen in fairly covalent compounds.

 

The "oxidation" and "reduction" may not be identical in definition with respect to organic compounds and actual redox reactions. Organic compounds can be oxidized or reduced; the carbon that is oxidized for instance, the secondary alcohol carbon to the carbonyl carbon of a ketone, is going to have an altered oxidation state as a result. You may or may not have been taught how to derive the numerical value for this concept on a particular atom in an organic compound but it isn't essentially equivalent to the formal charge.