How do in-progress school forms auto-save? Automatically per textbox, or if they click 'Next'?

We have an extensive admissions/enrollment packet with several subsections built into a school form.

As the title, if parents are in progress and working on a school form, does it save automatically as they type out into the field forms within a section, or only if they hit ‘Next’?

Just wondering how progress is saved if a parent were working on a school form over the span of a couple days.

Thanks!