A crucial factor in especially minimum ventilation is mixing the cold air from outside with the warm air in the house. To make that happen, the air has to travel far enough into the house before it loses speed and start falling down to the bottom.
To obtain enough velocity to get the air to the center of the house, it is important to have enough air velocity through the inlets. In this way the air picks up enough speed to travel under the ceiling of the house to the middle, and on its way mixes with the warm air that is gathered under the ceiling of the house.
To get the air far enough into the house, the air should not or as least as possible be blocked by obstacles under the ceiling like beams, lamps etc.
Also the inlets should direct the air slightly upwards towards the middle of the house. One can imagine that directing the air straight up to the ceiling will let the air "bump" against the ceiling and lose velocity. Also directing the air to the floor will not result in a good mixing with the warm air under the ceiling.
The air speed in the inlets should be high enough to reach the center of the house. As a rule of thumb, the air travels 1.5 times the distance in meters as the air speed through the inlets in m/s. So if the air speed in the inlets is 4 m/s, we can expect 4 x 1,5 is 6 m of distance that the air will cover before it loses so much velocity that it start to sink to the floor. This means that with a house of 12 m wide, an air velocity through the inlets of 4 m/s is sufficient to get the air to the middle, but in a house of 18 m, the air speed needs to be 6 m wide. Practically it means that the air speed should be 06/0,7 times the half width of the house, or 1/3 of the total widht of the house.
Next to giving the air the right speed and the right direction, also the inlet opening is important to allow the air to form a "beam" towards the center of the house. The correct opening in minimum ventilation mode is approx 2-2,5 cm. If the opening is less, the air will start to become too much turbulent, and the maximum distance will not be reached, even if the air velocity is correct. If the opening is wider than 2-2,5 cm, than the beam will spread out too early, and we also lose velocity.
If the ventilation rate requires less volume of air exchange, we still want to use the 2,5 cm width at the required air velocity, which means we have to close some inlets to get to the right air volume.