Control cards are often handy to overwrite local values. A good example would be if we need all parts to use a certain element formulation THEORY which is specified in *CONTROL_SHELL. As with any global control cards that manipulate local values, the global values specified in *CONTROL keywords are used ONLY if the local values are either zero or blank. If any of the parts that uses a SECTION_SHELL keyword whose ELFORM parameter is non-zero, then THEORY is ignored and the value from ELFORM will be used.
An exception that I recently found is in the values ISOLID, IBEAM, ISHELL and ISOLID found in *CONTROL_IMPLICIT_EIGENVALUES keyword. These element formulation parameters were originally implemented for handling NASTRAN input files read using *INCLUDE_NASTRAN but it applies for now for any model. Unlike other global value setting, these values overwrite all local values irrespective of them being ZERO or blank.