Best Of

My best practice is to practice!

Don't want until there is a production issue to get comfortable with doing a hot fix or unlinking a revision tag via a history roll back. This will feel daunting and scary in a production model but if you can practice in training/sandbox models that can help you get comfortable with the steps. The key is executing in the correct sequence of step and a firm understanding of how to utilize the model history to your benefit.

A few resources to help you learn the process:

Five questions and each question in itself is an ocean: Let me reply in a succinct way possible

What is your overall approach to managing changes to your Anaplan environment? ALM is the way to go. I will not add more to it as it has been covered by most of the community members. However, documenting tags is something which becomes extremely important - usually History ID with the sequential order is widely accepted (History ID because you immediately know if you have to restore the model, which History ID should be used to go back). In some cases, creating a separate list of Revision tags and documenting them in the list is also accepted (I personally have never done that)
How often do you deploy changes to Anaplan? It depends what stage of Implementation are you at. If you are still in Dev stage you can deploy changes almost every day but if the model is live and users are actively using the model, then there has to be a governance around it. Usually once a week is something we consider - ideally frequency of it comes from the Client but recommendations are provided by Anaplan consulting team.
How do you organize your models around your testing strategies? We create separate testing model for the testers to test with the dummy data. We also create Pre-Prod environment for end users to test with nearly Production data (sanitized prod data) so that they can get confidence in the system by testing with the numbers that they understand.
How do you coordinate changes between UX pages and data integrations in conjunction with model changes? We document all the changes related to the revision tag prior to pushing the tags to Prod. If there are any UX changes involved they are documented well in advance and as soon as the tags are pushed, UX changes are made immediately. If Data Integrations needs to run after UX changes are published - then we explore the possibility of adhoc runs/manual runs. We don't trouble IT team for such adhoc runs if all the data is within Hub.
Are you leveraging APIs to synchronize deployments across multiple models? No, never!