Outlook - Ways to add an additional mailbox explained

There are multiple ways to add an extra mailbox to Outlook. The methods I am aware of are:

1. Auto mapping - Grant full access to a mailbox in Exchange and the mailbox is added automatically in Outlook.
2. Add the mailbox as an extra account in Outlook (options -> info -> add account).
3. Use the "Open additional mailboxes" in the E-mail profile.

I've never found clear explanation when to use a certain method and when not and what are the (dis)advantages of each method. Can somebody point me to a website that explains this or explain this to me?