Estimated duration is drawn from routines and products, and once they're set up these will carry over into generated tasks and defect quotes and is a calculation factor in profitability reports.
Setting up estimated duration on routines
Go to a property and click on Routines > Manage routine services
Select a service level to edit by clicking on the level, then you can add estimated duration and click save.
When inputting duration you need to give a whole number followed by either h (hours) or m (minutes). For example input 2h, 30m for 2 hours and 30 mins (2.5 hours). Alternatively a decimal point value followed by h (hours) can also be used, 2.5h will give you the same result 2h, 30m.
Setting up estimated duration on products
Click on Billing > Product Catalog, then click View next to the product. From there you can click Update, and then you can input the time in the Estimated time field. The same options are also available if you're creating a new product (Billing > Product Catalog > Create product).
When inputting estimated time against a product, you only have to give a number in minutes (i.e. 120 = 120 minutes = 2 hours). This duration will be included in defect quotes