Here are a few things I have learned doing analysis in GA:
Unfortunately, the metrics are often flawed, so don't obsess too much about it, but keep the limitations in mind:
- Depending if your calculation for Time on Page could include or excludes exits (or bounces), it will most likely inaccurately report actual time on the page. (too short in one case, too long in the other)
- You still cannot determine the actual length of time spent on exit pages - since there is no event to track (ex: visit on a subsequent page. Therefore, this number can also be way off.