Delta revisions on Symantec's Internet LU servers?

How many delta revisions does Symantec maintain on their Internet LiveUpdate servers?

I've found one post from 2011 by a Symantec employee stating "I believe we keep 7 days of delta files" but no other sources, and I am wondering if this is accurate and still the case.  7 days worth of revisions seems a little low for providing updates globally.

Original post: https://www-secure.symantec.com/connect/forums/sep-average-update-size#comment-6148141

Thanks!