I use my instinct every day for walks. Today, I walked two miles checked the mileage when I got back to my office (two miles), but forgot to end the activity. Somehow, in the 20 minutes I was sitting at my desk I walked another mile? The posted activity says I walked three miles. I always do this walk, it's always two miles. I even plotted it on google maps thinking that somehow something got messed up and it confirmed that my walk was 2 miles. This is a huge problem if the algorithm if it's using time instead of actual GPS or steps.