Inventory management is a science in itself as inventory that is easy to source, such as wood stain or nails/screws, can be left in the suppliers inventory until you need it. However, if the local supplier is 2 hours away, then you need to carry more inventory based on time efficiency.
However, if there are some items, like specialized woods for instance, that are hard to locate, you may need to care more of that in your inventory because of unstable supply.
In other words there is no exact science to inventory management, it is all based on your unique business and your supply chain realities. Which by the way is always shifting and changing. Oh the adventures of business!