To allow you to manage a custom duration of Transfers you would need to do two things:

1. Create a new Custom Field to store the ending date and time 
2. Modify the Calendar View to use this new field

Go to any Transfer and open Odoo Studio

Drag a new Date/Time field to the Form to sit beneath the Scheduled Date:

In our case we have labeled the field Until with a technical name of x_studio_until:

Now we can enter the end Date/Time of the transfer.

Modify the Calendar View in Studio to use this new field:

You can now have 3 hour long Transfers scheduled in the Calendar:

Please work with your Odoo Digital Advisor or your Odoo Partner if you need further help.