This is a personal decision, but we recommend naming multiple people for each of the roles in your Tomorrow. You will choose one person as the primary candidate and others as backups (arranged left to right in order of priority). For example, if your primary guardian/executor/trustee is unable to fulfill the responsibility, the backup would step into the role (subject to court approval).
Remember, you can add people to a role and remove them from that role at any time. If you happen to change these roles, be sure to update and execute a new version of your will.
Feel free to reach out with questions or feedback: firstname.lastname@example.org