as long as you have already run enablecore.bin at least once and/or flashed 0.96 at least once you should not need to run it.

/etc/init.d/cgminer.sh before starting cgminer go through all the cores and enable them.

I don't rember where (and I don't have time know to look up for the post, pardom me if you can) but I read that one of the first fw (0.90 maybe) wrote the map of bad core on asic eprom and there was no way to overwrite it at runtime. that's the reason why knc release enablecore.bin.