The batch size always depends on a part. Basically if you want me to make you some stuff, you need to give me all the norms and all the specifications you deem to be important, so I can set up my production and quality control.
After that, there is a part approval process, which is a hardcore version of the following:
- I make some paperwork that everything is OK on my side.
- I make initial samples, send them to you, you take them apart and give me green, yellow or red light.
- I set up the production tools and start making beta samples.
- Then you send your people to audit my processes - and you will send the most fierce evil people you can find so they find any nonconformity even the smallest one.
- I ship you another batch or two/three/four, you set up your processes based on this second/third/fourth... batch. During this series I set up additional and tune my production equipment.
- After that comes the 2 day test production, where I demonstrate the capability of manufacturing required amount of part of the required quality. You also send some of your people to observe that I don't cheat.
- Then, after a while, you audit me once again - to check that I've fixed everything.
- After that I send you some parts with increased quality control both yours and mine.
- And after a while (which can be several tens of thousand parts) you allow me to remove some obsolete quality control measures.
This 'dance' can usually take about an year, but also can be shortened (if we already collaborated on a same product), but is seldom shorter than half a year (well, I've seen a production for a new product being set up under three months, audits, paperwork, machines and everything, but those guys were crazy...)
So, there is a very small chance that AMD didn't noticed those problems before.