I have to agree with you Tapehead.

Although, as someone else said, you often need a new piece urgently and 6-8 weeks can be a long time to wait & cope, so you order a stock.
Having just spent money on a stock, you're not always in the position to order a custom at the same time.
You can get in to a difficult cycle.
This is why I (and loads of others) always recommend having a quality 'spare' at all times!