There is a weird and hard-to-implement DRC rule that restricts uncontacted local interconnect to an aspect ratio of 10:1. Possibly you can get around that rule by specifically declaring the local interconnect to be a resistor. Regardless, any long wire of local interconnect should be treated much the same way as you would a long wire of polysilicon: Something to avoid unless you're okay with a high resistance. TiN has a resistivity that is about 1/3 of polysilicon, but that's many times more than the resistivity of any metal layer.