Configuring data factory pipeline alerts

I have read he documentation for ADF Pipeline alerts and an working to understand why a pipeline triggered an alert and yet in ADF Monitoring no pipelines failed in the period.

Some questions

1) Can a pipeline have an error fail and retry and that adds to the counters that might trigger the threshold for an alert? 

2) What is the way to calculate or otherwise determine the settings for the granularity and frequency when setting a metric alert like the failed pipelines one?

Cheers

Peter