Here is how you can add and use work amount information in Sitedrive.
Work amount information can be added to the work package. Work amount combined with planned efficiency can be used to schedule the durations for work packages.
How do I add work amount?
1. Open your schedule view in Gantt mode.
2. Add the Work amount column by click on three dot on the left side of the Work package column title 
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3. Select Work amount and Planned efficiency.
4. Input the work amount for each work package. You can either add the work amount to a sum workpackage which will divide the work amount to each sub work package, or you can add the work amount separately to each work package.
or
If your account has the Quantity based scheduling feature, you can read more about it here.
5. You can then add the planned efficiency and Sitedrive will adjust the duration of the work package accordingly. 