I just want to chime in to concur with Tom’s observation that some genealogy software does support RM’s source templates as they are exported in RM’s GEDCOM. I personally use some genealogy software along with RM that does support RM’s source templates as they are exported in RM’s GEDCOM.
But some genealogy software does not support RM’s source templates as they are exported in RM’s GEDCOM. And the direct interfaces to Ancestry and FamilySearch do not use GEDCOM. In neither Ancestry nor FamilySearch does the direct interface provide RM any way of passing source templates along. So Ancestry and FamilySearch are prime examples of where RM’s citations sometimes cannot be replicated correctly in third party software when an RM source template does not comply with the “left part” and “right part” requirement.
I get around the problem by using source templates of my own design that only have a “left part”, so it’s impossible for the “left parts” and the “right parts” to become mixed up. But that’s an unusual way to approach the problem. You could use templates of your own design that comply with the “left part” and “right part” requirement. Or you can make a copy of any of RM’s source templates that have the problem and adjust them a bit so that they comply with the "left part and “right part” requirements. Another solution is free form templates, whether it be RM’s built-in free form template or the enhanced free form templates that Tom describes.
Those are really all the solutions there are. I’m not sure that any one of them is a universal best practice. You will just need to choose the solution that best meets your needs.