Any plane will fly better when balanced laterally. If the lateral balance is off it can be corrected with aileron trim which makes the plane appear to fly OK. The problem with using trim to correct the lateral balance will become apparent when doing loops and flying inverted. The heavy wing will need it's aileron drooped so the plane will fly level with hands off in upright flight but when inverted, the aileron on that wing is now angled slightly up which forces the already heavy wing down even more. The other problem with the lateral balance being off is when the plane approaches stall speed, the heavy wing will tend to drop. As mentioned above, always add the weight to the wing tip and as close to the CG as possible.