A few rules of thumb to keep in mind when selecting your convergence:
1. The longer the convergence setting, the less meaningful it is to converge. The guns have scatter. At 400+ yards it is already significant enough that the bullets from one gun will disperse all over the target anyway. There is little point to argue about whether 500 or 600 is better.
2. The effective shooting range is twice your convergence - the bullets fly in an "X" pattern. At twice your convergence, the distance between the centers of the stream will be the same as the distance between the left/right guns on your wings. Set your convergence to 200 yards and at 400 or above you are not likely to hit with more than 1 set of guns. In particular, there will not be any bullets hitting your aiming point and the two streams will go crossed-eyed on both sides of the aiming dot.
3. The "in convergence" range interval is up to half your convergence setting - So if you set your guns to 300 yards, then between 150 and 450 yards (300+-300/2) the distance between your left/right aiming points is less then the distance between your centerline and the guns on your wing, which can be considered as close enough to be converged on a target wing root for example. This is why staggering 250,300,350 is not so bad because their convergence interval overlaps significantly. It is usually a very bad idea to spread them even more to where their convergence zones do not mostly overlap. Short convergence setting makes this zone smaller.
(This is a vague definition, so for planes with widely spread guns some may consider 1/4 of the convergence range are their "in-convergence" interval - i.e. all aiming points are less then 1/2 the distance between your fuselage and your guns.)
The above 3 rules are rough estimates that change a little from plane to plane depending on the length of the baseline between the guns. 190s, and 205 have wingroot guns so they always tend to be closer to convergence then the guns on the P47N that are WAY out there.
So, you see that the exact convergence is important only if you set it very short. If you like setting it to around 200 yards then fine tuning is important. If on the other hand they are set to the 300-400'ish ranges, the exact configuration (staggered, concentrated, +- 50 yards tweaks) is not very important.
With some very low velocity cannons, the convergence distance also affects the aiming point in the up/down direction. Some people set the 262 guns (nose mounted, so no left/right issues) to a pair at max and a pair at min to create a shotgun pattern - in the case of the 30mm you only need to connect with a single hit, so maximizing the chance to hit may be more important than max damage.