Is there a measurement that can be taken on such things to determine when rebuilding columnstore indexes would actually benefit from a rebuild?
Yes. Here's an article introducing it.
The goal is to have an even distribution of rows across the total_rows.
Did you forget the article?
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2