Why is it preferable to compare ratios calculated using financial statements
 that are dated at the same point in time during the year?

Comparing financial statements from different points in the year can result in inaccurate and misleading analysis due to the effects of seasonality. Levels of current assets can fluctuate significantly, depending on a company’s business, so statements from the same month or year end should be used in the analysis to ensure valid comparisons of performance.