By the time the Battle of Britain was in earnest, German fighter escort doctrine had changed.

During the Battle of France, three months earlier, the German fighters gave support to the bombers by flying a sweep ahead of them (Freie Jagd) or by patrolling a certain sector of the front, like the target area, where the bombers were due to appear (Jagdschutz).

The Germans found that the sweep produced the most kills, but the protection afforded to the bombers was insufficient. The Jagdschutz gave more (but still inadequate) protection, at the cost of fewer kills.
Escort was a difficult mission to execute since the bombers flew much slower than the fighters. As a result, the latter had to fly at a very slow speed (making them vulnerable) or at their normal cruise speed weaving around the bombers (which reduced their combat radius significantly). Furthermore, if the bombers were late, the sweep ahead of them became less effective since the enemy fighters arriving late had a free path to the bombers.

1. Galland came up with the scheme shown in the infographic. One Jagdgeschwader (fighter wing) provided escort to one Kampfgeschwader (bomber wing). The bombers had to fly close together and one of the fighter Gruppen provided close escort with instructions to keep close to the bombers all the time and only attack those enemy fighters that actually came to attack. One Gruppe flew detached escort, meaning that they were within visual distance of the bombers but could attack any enemy formation that got too close to the bombers. After the combat, these fighters were supposed to try to re-establish contact with the bomber ban.

The last Gruppe flew the free sweep ahead of the bombers and had maximum flexibility.

This escort proved too weak to support the Ju 87 Stukas, and orders came to use three Fighter Gruppen to escort each Stuka Gruppe. The close escort had to dive with the dive-bombers since the British carried out their most intensive attack after the Stukas had bombed and were more vulnerable.