Coming from the media world, our content creators live and breathe "time spent" metrics, as they provide one of the best signals of engagement. Problem is the time spent metric in Analytics is seriously flawed - it ignores time spent on visits that bounce, it doesn't take into account user inactivity, etc. and only records time elapsed from one page load to the next. As a result, we often end up with unrealistic time spent numbers that are frankly hard for our analytics team to defend.
Other companies (e.g. Chartbeat) solve this by continually pinging a user's browser, and checking to see whether that user is still active, providing us with far more realistic and actionable time spent metrics (and also some nice "% of page viewed" metrics that includes bounces). Adobe appears to have moved in the continual tracking direction with their video tracking, but haven't applied the same logic to their "traditional" analytics reporting. Seems like a big missed opportunity for their media clients in particular.