This kind of question crops up frequently since we're continually producing new EBS updates. There is no definitive right answer. For example, the answer depends upon:
What is a Recommended Patch Collection?
Recommended Patch Collections (RPC) are collections of patches that we have already released individually for EBS 12.1.3.
Customers can apply individual patches or they can apply a Recommended Patch Collection. Either approach is fine.
We periodically bundle the latest patches together to save you the trouble of applying them individually. As an added bonus, all patches in a given RPC are tested together for compatibility, which isn't always true for individual patches that are released on an emergency basis.
Recommended Patch Collections are not a “release.” We currently have no plans to make a specific RPC a minimum baseline or prerequisite for new EBS 12.1 patches.
What is our policy for releasing EBS patches?
Our official policy for releasing EBS 12.1 and 12.2 patches is published here:
What's the best strategy for applying EBS 12.1.3 Recommended Patch Collections?
We generally recommend applying the latest EBS updates to production as soon as it's convenient for your users.
If you're in the middle of testing a specific RPC and it's too late to switch to a newer one, go ahead and complete your patching project on production. You can always apply the next RPC in a subsequent project.