Fast Corner estimation for older devices

Yep, Quartus and hardware has come a long way...

The addage I remember from around that time was, "compile for the fastest speed grade, then divide that number by 4". That's probably really pessimistic, but should cover all conditions. (Be careful though. If you're doing Tpds and there's a lot of logic between pins, you might have multiple paths between those pins. This is an estimate on only one of those paths, most likely the longest, but if you have a shorter path, that's the one that should be used.)