@Matthew_Willcock
I think you can achieve your hope with below( To get results in hours (with decimals)).
when you create a formula field above, you’ll get estimated time in hours(dicimal).
If you want to get it in days(dicimal), use (# Estimated time + 0)/60/7.
According to your explanation, your leadership recognize 7 hours as a day.So you can divide with 7.
