I’m not sure why I hadn’t noticed this before, or why it suddenly seemed like such a novel concept to me, but while I was running a backup command one on SQL I realized what the STATS keyword actually does (red circle below).
Then it hit me, it’s the interval that reports the percentage of the backup that is being backed up.
And just to make sure that’s what it was doing, and that I hadn’t just made this up, I looked up the backup command on BOL.
STATS [ = percentage ] Displays a message each time another percentage completes, and is used to gauge progress. If percentage is omitted, SQL Server displays a message after each 10 percent is completed.
The STATS option reports the percentage complete as of the threshold for reporting the next interval. This is at approximately the specified percentage; for example, with STATS=10, if the amount completed is 40 percent, the option might display 43 percent. For large backup sets, this is not a problem, because the percentage complete moves very slowly between completed I/O calls.
So there ya go, a little bit of knowledge in case you didn’t know, or hadn’t thought about it as I obviously hadn’t.