Part of the reason that the GL gets out of whack is that it is all too easy to buy a part against one GL account and then issue it from inventory against a different GL account.
For example:
I can explain some other scenarios, too.
Really, all you have to do is change a part class on a part and boom, GL is off at the very next transaction.
Or the people that make a PO for some MRO item (coffee, for example) and choose a part class that goes to inventory or R&D or anything but the right place.