That is a commercial engine. Even 1% fuel savings is critical for success, so they do several redesigns and testing. Safety tests, certifications also take much, much longer. If you get sued for causing a death by skipping a test or civil certification step that take many years, you will lose billions of dollars. Not that state allows you to skip it.
Militaries especially in wartime can cut that time down to a few years at most not 10 years by ignoring fuel economy, top performance and safety norms for certification. Akşit always talks about civil certification time. Do you think TAF will give a flying f about minor safety risks if a war breaks out? Which can break any second due to our “friends” in NATO.
You can speed up the process 3x simply by running 3 8-hour shifts without holidays. There is 3d printing that wasn't available during that 10 year time frame standard established. Also, digital twin wasn't factored in to that 10 years.
America was producing 300 planes and 6 ships a day in WW2. 70+ years ago, FFS. That was declared ridiculously “impossible” by top American nay sayer experts then, too. And then an engineer that built Hoover Dam in record time by using smart new techniques like using water pipes to cool down and speed up cement curing time was appointed as the head of those nay sayer experts. Rest is history…
When the Wright brothers were about to fly their first plane, nay sayer aviation “experts” were saying it would take at least a million to 10 million years for a man to fly… Lack of imagination, on the part of uninspired millions, can't slow down bright people.