Multiple form groups, or just one?

I am currently building a front-end submission page, where I want a bit more control over how the form is displayed.

For this, I am thinking of splitting the front-end submission into multiple field groups.
However, I see that each field group gets its own submit button.

Is there a way to only have one submit button for all field groups, and submit them so that only ONE post is created with all the custom fields?

Or do I need to use only one field group, otherwise it won't work?