Increasing activity Duration on customer activities

Summary:

For specific hand-picked activities we want to be able to increase the activity duration. Our customer activities have 'Calculate activity duration using statistics' enabled in activity type, therefore are not allowing us to change the activity duration.

Content (required):

We have cases where for a specific work order we know the duration will be much longer than what is calculated in statistics. We want to set the desired duration so the routing engine can take it in consideration when routing the activity. Otherwise the tech could receive more work than he/she can perform that day.

Version (include the version you are using, if applicable):