I just ran the additional test I noted above. I went into Google Maps and had it locate my position. Then I did a new backup to look at the data again.

I had 9 additional records, all Timestamped identically, from while I was using Google Maps. However, there were 112 other records where the Timestamp was updated.

So again, it seems to only update the database when you use a Location Based Service. And it does update any existing records with a current timestamp.