Garmin shows total number of runs both on the watch and in the app. Presumably it means that this info is stored in the FIT file. Is there a way to have total number of runs shown in the Intervals Activity? If yes, how? If no, then this becomes a feature request.
Cheers!
Custom fields. Doesn’t look like anyone has put one together for this specific value, but they are fairly simple to add.
Click
Custom, Add Field, The 
under FIT file field, and the field should be in the dropdown. If it isn’t, you can set the field number manually.
Perfect. Exactly what was needed.
I created Number of Runs (num_laps) and made it public for others.