Hi again,
In another document from the same archive, the average size of the aiming error is quantified as part of a training document (addressing the gunnery instructors):
[URL unfurl="true"]https://invenio.bundesarchiv.de/invenio/direktlink/342fff41-bf0b-4fc3-9ccf-f593c0e4923a/[/URL]
From p. 10 by slider count:
"Die Auswertung von Frontfilmen und Schiessversuche haben ergeben, dass ein Durchschnittsschütze beim Beschuss bewegter Ziele die Hälfte der von ihm abgegebenen Schüsse in 100 m Entfernung in einen Kreis von 2 m Durchmesser zu bringen vermag. Der Radius des 50%igen Streukreises beträgt somit in 100 m Entfernung 1 m, in 1000 m Entfernung 10 m."
Translation:
"The evaluation of gun camera footage and gunnery trials have shown that an average shooter firing at moving targets is able to place half of the shots he fires in a 2 m diameter circle at 100 m range. The radius of the 50% dispersion circle thus amounts to 1 m at 100 m range, to 10 m at 1000 m range."
In other words, an average shooter will hit 50% of his shots in a 20 mil diameter circle. For comparison, the Luftwaffe's gunsight reticle according to the same document is 100 mil in diameter.
From the high priority assigned to the yaw damper, I would conclude that probably the Luftwaffe found that with the help of the yaw damper, an average pilot was able to significantly reduce the size of that circle.
Of course, the good shots could probably achieve a much smaller diameter for their 50% circle ... Eglin Air Foce Base test pilot Don Lopez in "Fighter Pilot's Heaven" notes that in his gun-camera recorded tracking tests, the optimum tracking result he achieved was an accuracy of 0.5 mils - dramatically smaller than the 10 mil the Luftwaffe expected. This was not in a combat situation though, and he had been flying a long series of similar gunnery trials, so he had gotten extremely good at tracking. He actually mentions that a tracking accuracy of 6 mils was considered acceptable by the US ... pretty close to the Luftwaffe's 10 mil figure for actual combat gunnery.
(The often-quoted "only 2% hits" figure for Luftwaffe service pilots is a myth, by the way - most likely a misunderstanding of Ballistic Laboratory Report 727 by Herbert K. Weiss, which notes low hit percentages based on gun camera films. However, if one reads the report carefully, it's clear that Weiss talks about discernible hits, which are only a percentage of all hits score, since not all hits produced "visual effects" clear enough to be recorded on film. Weiss points out that there were kills scored/fires started from attack runs without any discernible hits! 
)
Regards,
Henning (HoHun)
