Thank you all, that does help a lot.
@MikeGross “Hierarchy” meaning like Bryan said, you routinely need the Inventory Transaction Hierarchy guide to figure out why a transaction hit a certain account, if you notice it at all. Classic is this one, where the shipment and mtl-issue hierarchy has it look to the Part GL Code, then class GLC, while PUR-UKN looks to class first and never looks at the Part GLC. So you might buy to a different account than you issue from.
@Randy Those are a must. They are on my desktop and always have been.