Correct Yuval did say at the agm that the only reason the phase...

Correct
Yuval did say at the agm that the only reason the phase 3 did not work was due to contamination in a glue, that it took the fab 8 mths to isolate.
Your comment re competitive advantage is the key in my book also.
Apple is selling around 300 million phones pa. At $500 each that is s massive number, which they would likely want to maintain or grow.