ok . Let me explain in simple terms . As it’s the same principle as the British army
If you was to join the US army as a chef , you would complete MOS (basic) training then go on to do your specific training to be a chef .
If however you was to join as a tank crew member or an infantrymen . You do NOT complete MOS . You do not even go on that course . Instead you go and complete OSUT . Which is a single 16 weeks course that COMBINES the mos , AIT and job specific training .
YOU DO NOT DO BOTH COURSES
So total training length for an infantryman is 14-16 weeks .
I even found a little source or two ,to back me up with