Why downard trends based on rolling periods are different

The precaution of using the end of calendar period FLI is not required if the periods in the Trend are rolling periods, because in that case the most recent period is already a complete period and the trend therefore does not need to wait additional time until all of its data is collected. It is only when the periods are calendar periods that the most recent period can be still incomplete and require an end of calendar period FLI to properly time the final trend evaluation.