If you are in the JIT logistics game there is a lot that can go wrong.
Tell me about it! In reality, the problem is that my small biz is just getting over the hump of being able to produce the product faster than the build up in demand. Early in the process, there were a ton of revisions, tweaks, software, etc. All that in addition to figuring out a shipping system, storage, website, all the back office junk.
The problem is not really the customers, but more on my end trying to work out the production chain. My product has a little over 400 parts and I do all of it soup to nuts. Design, mechanical engineering, electrical engineering, software, PCB assy, 5 axis CNC machining, inventory and purchasing, website. I am slowly automating everything starting with the P&P, then all the production test and measurement with LabView. Ordering and shipping is being automated too. Trying to see how far I can get on my own focusing on automation. Starting to outsource the CNC parts now that the design is stable and documented. When the design is fluid, it is impossible to outsource. Machining the parts myself is a huge help to optimize the designs for manufacturing without compromising the function. Since I do all the mechanics, the 7 PCB's fit in like a well considered puzzle because they were designed with the mechanics.
It may be more clear why I am sensitive about reliability with my equipment. If the P&P stops working - it falls on me to hand place PCB's until it gets fixed which is also done by me as well. I hand placed many 10's of thousands of parts to save enough money to get all this going so at least I am very accomplished at hand building PCB's with lots of fine pitch parts on double sided PCB's.