Adding salt to a marinade to brine?
Marinating is basically a surface treatment.  Marinades don't penetrate more than a millimeter or two.  Most flavor molecules are just too large. So, if you like the flavor after a short bath, just keep it at that.  A longer marination generally doesn't help.
Now, salt does penetrate, that is why brining works.  However, don't confuse brining with marination.  The added salt will not improve the effect of marination.  Only the salt will penetrate.
These are two different processes.