How to get big-picture feedback from advisors, rather than just details, during fieldwork
You need multiple mentors for different purposes.  In my experience, some very experienced faculty cannot see the big picture of their research, but provide excellent advice about the details.  Some similarly experienced faculty can only give advice on the big picture and will pay no attention to details.  Seek mentors with a diversity of strength.  

You can also try asking your mentors explicitly for broader advice.  I've had mixed results doing that.