Deflection shooting was a very hard skill for pilots to master, one of the qualities that separated the small percentage of aces from the majority of combat pilots; "... not many pilots ever mastered [deflection shooting], and... the majority of kills were made from within 15 degrees of dead astern" (Stephen Bungay, Most Dangerous Enemy). "Pilots consistently underdeflected in action because they seldom had a training target capable of a realistic combat speed on the few occasions when live bullets were used" (Mike Crosley, They Gave Me A Seafire). Gyro gunsights helped greatly though were by no means infallible, before radar ranging was incorporated pilots had to manually adjust the range to the target and the target had to be smoothly tracked.

In the grand scheme of things, though, by the time the RAF Gyro Gunsight Mk IID and US-built equivalents, the K-14 and Mk 18, were introduced in quantity in mid-to-late 1944 the German and Japanese air forces were already at breaking point so the gunsights themselves were not a deciding factor in air combat.