Hey Jeff,
Thanks for reaching out! This is not easily possible:
If an event at Venue A existed for January 14 from 4pm – 6pm, is there a way I could stop other submissions from being submitted that would overlap that time in that venue?
If you’re comfortable with coding, then you might be able to dive under the hood and tinker to fix this; but it would indeed be a rather involved customization. There is no support for this with the plugin as it stands “out of the box.”
Though it’s of course not nearly as robust, a useful feature that is included out of the box here might be the fact that you can set the default status for events upon submission; this way, submissions can be set to come into the site as “Draft” items, or as “Pending Review” items, instead of “Published” items. This would mean a manual review and approval before they are published, which may or may not suit your project’s needs well but I just wanted to mention it.
Let me know if this helps and if you have any other questions I can try to help with.
Sincerely,
George