I presume you encounter them later on. Maybe while doing more ground-level thinking about how to actually implement your meta-ethics you realise that it isn't quite coherent.

I'm not sure if this flying-by-the-seat-of-your-pants approach is best, but as has been pointed out before, there are costs associated with taking too long as well as with not being careful enough, there must come a point where the risk is too small and the time it would take to fix it too long.