Why might the Both Method be preferred to either the Incurred or Paid Methods for a Reserve Analysis?

One of the procedures that the Both Method does is to look for years where the reported Incurred Losses are equal to the reported Paid Losses.  In these situations, Loss Forecaster presumes the period to be closed and does not develop the losses any further.
 
However, for the Incurred Only and Paid Only Methods, no such test is completed and every period is assumed to be open.  Therefore, all losses are developed.
 
Using the Both Method may be the preferred method, since it appropriately considers any years that are closed out.