Each battle had different dynamics of aerial warfare, but ground assault craft, which would be the gunner's primary target primarily came in shifts. As seen with Kursk, for example, it wasn't really that both sides were sending in close air support at the same time. The German wave would hit, then re-arm, then the Soviet wave would hit then re-arm. This was in part because they tended to fly missions en masse, thankst to the relatively small amounts of potential air time, low munitions transport capability and the general inaccuracy of air support, and as such leaving at a different time tended to naturally result in a cyclical approach.