What does "Behavior Tagging" do in Mi Fit app?
Does the Mi Band "learn" what each activity 'looks like' so it tracks it automatically?
If so, how often should I use it until it has enough data?
Looks like it gathers data and submits to Xiaomi. The data is used to train their system to recognize the activity you are performing at a given time. For more info, check this page: click here Hope that helps!