Hi Forum If I set all the required user and group assignments for all

As mentioned above, Users are not exported across instances. Appian's best practice is to either use Group or rule based assignment. This will allow for easier migration across environments.
If you assign a task directly to a user, upon importing on the target environment, the system will inspect for the availability of the same user (with the user id). If not found, it will raise an import error. Secondly, when a task is hard-coded to a user, & the user changes role, it will now require someone to update the mapping of the task to another person. For this reason, I'd recommend you architect your solution to use Group or Rule based assignment.

As mentioned above, Users are not exported across instances. Appian's best practice is to either use Group or rule based assignment. This will allow for easier migration across environments.
If you assign a task directly to a user, upon importing on the target environment, the system will inspect for the availability of the same user (with the user id). If not found, it will raise an import error. Secondly, when a task is hard-coded to a user, & the user changes role, it will now require someone to update the mapping of the task to another person. For this reason, I'd recommend you architect your solution to use Group or Rule based assignment.