Hi @avisekmondal,

What I have understood from your question, there are 2 parts to it.

1. Count/sum of cases

2. Average Time taken by user for cases

The solution can be approached in 2 ways:

1. Is there any OOTB way of achieve it. I will say it is not impossible but it is more complex to use just OOTB rules and do it. Although there are many OOTB reports which gives the time taken by user to complete case, throughput etc which you can refer in pega report browser

2. Create your own property like Start time/End Time etc and add values to it so that you can use it for reporting.

I had similar requirement in past for which I created a Data Type (table). Whenever the case enters the stage, you can add the case ID, date, start time, user name in the table and when the case moves out of the stage, add end time, etc

Now, you can create a report on this table to fetch anything you want as you will have all data handy.

As a best practice, please consider using Savable data page to add rows to the table. Also,in future you have to create a purge plan for this data table (based on create date or some flag etc) for which you can use a Job Scheduler.

Hope this helps!!