In Virginia we did things what I would could consider the "right" way:
There was a state standard for each event which would qualify you automatically. You could hit that mark any time during the season. You also qualified if you got top 6 at regionals, regardless of time. Regionals was similar, there was a (slower, obviously) time to get into that, or you could place top 6 at "districts" which were just 6-9 local schools thrown together. Everyone got to run at that meet, no qualifying or whatever.
I think having advancement by placing AND a qualifying time which you can run all throughout the season (not just at regionals or whatever) is the most fair way to do things.
Reading about that Texas mile with Steve Magness... a super fast state like Texas is just screaming for a time standard.
Also, in VA we said "states" ... and "soda" ... and "sub" ...