Let's say that someone wants to follow sage advice and properly setup TempDb and TempDb's log. But let's also say that the chosen sizes are almost certainly too big/aggressive. E.g. pretend we've got some extremes where TempDb's log is filling up a 250GB drive while there are 8 equally-sized TempDb files filling up a 1TB drive.
Is there a way to tell from a query that the sizes are "too big" after the server's been running under "normal" load for say a week or month? I.e. how would one gather enough information to make a reasonable, educated guess that a 25GB log and total 120GB of TempDB files are sufficient?
Or is there no other way except to shrink them down to "almost certainly too small", turn on auto-growth, and hope performance doesn't suffer too much for a few weeks while they grow to "proper sizes"? ...'cause that sure would suck.