What are best practices for changing a document's template?

[Peterson]

Advice I once got was, never attach a new template to an existing file. Always create a file based on the template, grab all content but the last paragraph mark from the old file, and paste into the new one.



I'm helping a colleague roll out a template to hundreds of users, and she doesn't see the need to do what I describe above.

I understand that the last paragraph contains an unseen section break containing commonly corruptible elements -- hence the reason for skipping it -- and I'm under the impression that this section break undergoes a sort of entropy over time, collecting "garbage," such that, Bad Things will eventually occur.

Two questions:

1. Is my paste-all-but-the-last-pilcrow-into-a-new-file method needlessly cautious, or a sound approach, in fact, a best practice?
2. Does the last pilcrow contain information about styles, or is it limited to other, unrelated document attributes?

My biggest concern is, if my approach is sound but not adopted, we're going to end up with a lot of corrupt files, as the template and the old docs both have complex list numbering, and many of the files have been recycled many times over the years.