Some of the filter examples and the questions they answer
When was I performing better than my average in the selected period?
Just filter the VMG>Selection Average
When was I gaining on the leading boat
Filter DTL Rate>0
What was my average heel on the upwind sailing for the whole day?
Select pure upwind sailing by using the Upwind legs, with no Maneuvers. Then add the free filter a bit below your typical VMG on the upwind for the conditions. The data fields show the heel angle of 1.02 degrees to windward for the filtered period of 27.5 minutes of pure upwind sailing.