Agreed - Avg Time Spent is my least favorite metric.
Customers that have a high time spent: Is that good news?
- it could be. Maybe these customers are highly engaged and just consuming tons of content.
- it could not. Maybe these customers are lost and frustrated and can't find what they're looking for.
Customers that have a low time spent: Is that good news?
- it could be. Maybe these customers are coming to the site to accomplish one thing, and they find it very fast and leave.
- it could not. Maybe these customers are coming to the site, don't instantly see what they're looking for, and leave.
Aside from that, it's even harder to take action from this metric:
Avg Time Spent is probably best used with highly targeted segmentation. If you're able to use segmentation to clearly distinguish 'successful' visits from 'unsuccessful' visits, you could then segment even further based on buckets of time spent, then dig into the paths that result in 'short' successful visits versus 'lengthy' successful visits. But once you've done this, how do you act? Which is preferred?
In the end, as JimKultgen says - align your metrics with your conversions: leads, revenue, orders, registrations, requests completed, etc.