If you're doing a castsequence, it would be a single macro.

The only time you'd want steps is when you want different actions on subsequent presses.
If there were a two-step mapped key, where you have a castsequence macro on keybind 1 and a proc macro on keybind 2...
And you wanted to alternate between them, you'd go for Steps.

Then likely have a castsequence on one macro.
And a macro and/or another castsequence on the second key.

If the macro (castsequence from the earlier post) is longer than 255 characters...
Make it as an IS Boxer macro action, instead of a keystroke action with the macro in Warcraft.