This is perhaps the most common reason for inaccurate ranging of storms. If two storms lie along the same line of azimuth, the results in the analysis window will be a single storm that lies midway between the two. The analysis performed is similar to statistical techniques used in predicting election results. Just as it's ill advised to make an election prediction based on polling too few voters, the ranging on small storms is only an approximation. Big storms will have a more squat appearance than small storms.
More strokes means more confidence in the ranging.
The stroke rate history graph shows you at a glance the rate of change of lightning activity.