Hi chickc,
Yes, the default is to show all items. Just to test this out and make sure I wasn’t crazy, I created a fresh WordPress site, went to Settings > Reading
to change the default to 5 posts and then created a FAQ page. I didn’t have any issues seeing all the FAQ items I created —
https://test.arconixpc.com/frequently-asked-questions/
The only thing on that page is [faq]
Off the top of my head, if you’re not setting showposts="5"
in your faq shortcode, I’m not sure why you’d be seeing any fewer than all the FAQ items.
It would seem to be either another plugin or the theme itself is coming in after my query is created and modifying the post parameters. If they were, this would be how: https://codex.www.ads-software.com/Plugin_API/Action_Reference/pre_get_posts