Hi Ben,
I don’t believe this is possible in Workfront. I periodically need to get a count on the number of tasks per project. I’ve found the quickest way to achieve this is to create a task report showing only project name and task number. I then export to Excel, hop over to the second tab (the data list), highlight the two columns, and insert a pivot table with “project name” on rows and “task number” on values (it defaults to “count”). You could then run an average on the resulting “count” column. It takes a couple of minutes all told…not as ideal as doing it in Workfront itself, but it works.
Kathy