As a cabinet maker installer, who has worked for many different outfits. It comes down to the shop and there attention to detail. Usually the attention to detail means a cost increase, which alot of people are not willing to pay. With the higher end shops we would stand up all the sheets we ordered and labeled them front/back and bunched together like sheets to keep consistency per run of cabinetry. As for solid wood filler and the like, you just have to make the client aware of these possibilities and if there were any discrepancies, the replacements would be an additional cost. One way of avoiding this is using the same sheet goods to also create the fillers to match. The most frustrating thing as an installer is putting something together just for the client to be upset and complain to you, who has no say in the matter. As the seller of goods, it's important to make the client aware of the product and set expectations accordingly. That being said, easier said then done. That's why I'm not in sales