late to game.. but

why did you AVG() on all the database files? Some databases could have multiple files(*.ndf) and many of them could be small, but any one of them could run wild.

Something I was looking for in this article was how to account for "free space" and autogrowth: What if a db file has an autogrow of 100MB, is currently allocated at 800MB, and is currently using 795MB. (let's say max size is 12000MB) If the database rarely grows, this alert would constantly nag. I would have to reallocate the database to 1000MB to avoid the alert (given a 20% threshold). That doesn't seem like the right way to mitigate the alert; translate this example to GB and it's a great waste of space. Do we compare against MaxSize? (what if allocation is unlimited?)

How are others accounting for this?