Agreed Kenny. A more interesting question is how to properly sight in wing mounted cannon and MGs when the projectiles do not have same ballistic coefficients nor ballistic paths.
You end up with some aircraft using MGs for ranging and cannon for final kill.
Your question has multiple answers dependent upon airframe, weapon system, pilot preference and mission context. Any single answer is dubious in my eyes.
On a side note, I do have 8th AAF tests patterns of B-17 and B-24 gun positions for 10rounds fired at 500yds. The results are varied dependent upon aircraft, turret vs handheld emplacement, and turret manufacturer. The stats also include % of attacks from 8 different compass points taken from ETO. Fascinating really.