Hey @tim2
Thanks for the feedback. We know that our philosophy on preview is different from most of the CMS out there, and I'll detail our view on this topic.
Why do we think our approach is better. Multiple preview session vs. A single Endpoint
The main difference between the other CMS in the market is that we offer multiple preview session. This means that an editor can work on a page without being impacted by someone else's changes. This is particularly helpful because another user could change a linked document or the navigation that might break the page that you're working on without you understanding why.
To answer the specific use case that you're describing (Multiple editions that you want to preview at the same time), we provide a feature that is called a release. To preview multiple documents simultaneously, we recommend putting those documents in a Release.
Once you've put those documents in a release, you will be able to preview all the changes simultaneously in your specific preview release session. Again by doing that, you will not impact any other user previewing their content, and we feel this is the way to go.
What you win on top of that, is that once your content is ready you’ll be able to publish or schedule the publication of all your changes at the same time.
You can see more details in this video.
Happy to hear your thoughts on this.