I was fortunate enough to work for the Lean Leader at GE Energy.  This is where, after getting my Green Belt, I was trained for the lean manufacturing.  Much of this was hands on training where a few times a quarter, they would hold Lean Events where they would bring in the team from Shingijutzu Corporation.  During these events, they would have someone, typically trained in the Toyota Production System to walk through our processes and help educate us to where our waste was and how we could run more efficiently.  I was involved in transforming one of the lines in Bangor from a Batch processing line to a Single Piece Flow.  This is where some of the benefits seemes to become obvious.  From there, we did several more projects and with similar results.  The Lead times for things was reduced as we eliminated a lot of the queue time and gave us the chance to reduce inventory.  

Going from these larger more focused events down to daily work and looking at processes has followed me throughout my career, and has changed my mindset from repairing a defect to preventing the root cause of the defect.

During my tenure at GE Oil and Gas, I had the opportunity to sit in on all of the APICS classes.  They provided a great deal of value, and at times in my career, I wish that everyone had taken those classes.  At the time in my career they reinforced the things that I always knew in my gut as well as some of the things I had learned from the education in Lean Manufacturing.  One of the most eye opening books that I have come across was a manual for Oracle.  I came across it shortly after taking the APICS courses where everything in the Oracle book was taught to us through the APICS class.  From Kanban, to Min-Max Planning, lead times, BOMs, etc.  It was one of the best examples that married the technology to the best practices in the industry.  The biggest take away for me from those classes is that there are different approach to managing the business, and the first question should be what type of business are you in.  This is often overlooked and people gravitate to what they know, not what is the most efficient way to run a business.  

Breaking down some of the more granular components, I have worked a great deal with the Work Orders (Production Orders, or whatever name you wish to call them).  NAV and Oracle treat these quite differently, and you need to know enough of the details to navigate to a solution that is best for you.  In Oracle, you can have multiple resources assigned to each operation, and NAV is (at least in the version I was using) is a 1:1 relationship.  This does not mean that things are impossible to do, but it does introduce different ways to get to the same goal.  Many people fail to realize that your Production order is similar to a Purchase order.  You can create it whenever you want, or when you see demand, but if you do, then you are creating something that you have to manage.  If there is a justification for doing it, the costs of maintaining it must also be weighed.  

I have seen and created solutions for a variety of things ranging from vendor driven operations (perhaps a coating, or stress relief) to rework, to parallel operations and everything in between.  The benefit that I have seen is not just the setting up of these objects, but the ability to understand how to pull the data on the back end and what it all means to the business.

In my experience, I have dealt a great deal with Engineering.  The objectives between Engineering and Manufacturing are often different and misunderstood.  It is important to connect the dots between these two organizations as the output of one is the input to the other.  Part of the confusion that I have seen is that Engineering may not fully see how purchasing buys things or the shop uses things.  For example, Engineering may consider a Stud and Nut as part of a kit, where purchasing buys them separately. The two departments must be aligned and the BOM elements must be structured properly to allow benefit to the entire organization.

Drilling down to Items, these are the foundation of how a business runs.  Ideally, they are categorized in such a way that makes things meaningful to the business.  For example, if someone wants to know how much was spent in fasteners last quarter, it should be an easy answer.  If you need to get a team to look at the item numbers, and break them down, then chances are that you are not setup properly.  Similarly, the top management should be able to tell things like what was the breakdown for revenue by product line last year.  If these questions are difficult for someone to answer, then likely the items have not been properly defined.  I could expand this part for a while, but there are things to consider like country of origin, documentation requirements, vendor restrictions, etc.  All of these will come into play during the setup and definition.