Try this on for size.

First off, I used the Format as Table function for both tables. When you see the formulas I used, the reason should be clear. Format as Table can be found on the Home Tab in the Styles section. Not only does it automatically format your table, but it makes formulas easier to read as well as lots of other things.

Anyhoo, to the right is the table I made. For each case, it calculates the time to progress between each phase and then gives the average for each.

See if this makes any sense for you. If you have any questions or need further help, let me know.

Attached Files

Sample Sheet SSO History.xlsx (12.2 KB, 13 views)