it's just an `is_callable` loop, not likely to be expensive though I haven't profiled it. That said it's code executed always to mitigate [your concerns expressed earlier](https://github.com/cakephp/cakephp/pull/2280#discussion_r7485698) which is logic that _probably_ will get very little use.

I'm fine with removing it, though perhaps validating settings is something that should be used for other things (cannot slug foo - foo isn't a field in this table, etc.)