Ability to add your own exercises if the database doesn’t contain it.
Too often a machine or general exercise isn’t in the data base so a substitute has to be found. The ability to add something would vastly improve tracking
Hayley Hatt commented
Or the ability to do a walk /run. As I'm just beggining my journey back in to running and getting healthy I walk predominantly, but have started running intervals in to my walks to build up to full runs, but that's hard to track as I am not stopping to watch time or distance I've walked and run in one workout.