Lovely question Colin. There is not a right-wrong answer – it all depends on what you are doing with the breath.
If you are focusing on PROJECTION of QI (which emphasises the Outer World) then IN-BREATH is used to build up the energy in the body and OUT-BREATH is used to project it outwards. This is what your pictures show. In that case it makes sense to talk of the Qi-Ball.
What we are doing in the first family Inner Qigong is focusing on CENTRING AND EXPANDING FROM THAT CENTRE TO THE EDGE OF OUR SPACE. We are not acting on the world, we are asserting ourselves.
In that case the IN-BREATH is used to FILL the BODY and FILL our personal space. But this outward movement is YIN. It is not acting on the world.
Then the OUT-BREATH can have two functions.
1) To SETTLE DOWNWARDS to accept the support of the expansion.
2) TO CONTINUE EXPANDING OUTWARDS but still not beyond our boundary. We are still asserting our space, not acting on the outer world. But this Large Intestine movement is more YANG. It actively pushes invaders out of our space. The expansion has a protective function as well as an assertive one.
The key idea is that the Large Intestine is a gentle giant. The outward pressure is soft and non-violent but also irresistible. It is not violent because you are coming from a place of ASSERTING yourself rather than DEFENDING yourself.