Could someone please help me understand this. I see some websites saying that the proper way to install Oblivion is to

1. Install the base game.
2. Install the non-SI 1.2.0.416 patch.
3. Install Shivering Isles.

But I've also seen other sites say this:

1. Install the base game.
2. Install the 1.1.511 patch.
3. Install Shivering Isles.
4. Install the SI 1.2.0.416 patch.

So I'm confused. Which one is the correct order? And where do these orders come from? Is there an issue with just installing the game and SI and then the latest patch?