Outlook Desktop users continually prompted for credentials On-Prem Exchange SE

That sounds frustrating. If recreating the Outlook profile only provides temporary relief, it may be worth checking whether the issue is related to Modern Authentication, Autodiscover configuration, Outlook build compatibility, or authentication settings on the Exchange server. Also review the Exchange health, IIS authentication logs, and Event Viewer on both the client and server to identify recurring authentication failures. It would also help to know if the prompts affect all users or only a specific group, as that can narrow down the root cause.