Time spent using mobile app - Average session length interpretation?

Hi All, 

Another question in my series of basic AA questions #noob 

I have been asked to find out "how much time do users spend on our mobile app". From the documentation and answers on this forum, it seems that the 'average session length (mobile)' is the correct calculated metric for this question. 

My question: 

1- How do we interpret the number? E.g. 00:30:00 for May'20 indicates that on average, people spent 30 mins using the app, across launches? This seems fairly high for a 'financial industry' app

2- If i want to do this for a particular page, would it be correct to add the specific page name as a dimension and then average session length as the metric?

3- How do you guys answer this business question - am i missing something? 

Thanks!