What is the level of database normalization that is "practically" enough?

Question

I am designing a database and I reached (as per my little knowledge) the Third Normal Form (3NF)

Some of my colleagues told me about a Sixth Normal Form!! I was wondering how to know if the level of normalization of database is enough.

Answer 1

In my experience, it's pretty rare to hear anyone talk about going beyond 3NF for real-world production applications. That should be sufficient for nearly all cases.