set_clock_groups vs. set_max_delay/set_min_delay

Good topic. From my experience, most users use set_clock_groups and I've never heard of a problem(at least one that would have been caught by set_max/min_delay). I believe it's a cleaner constraint(easier to read when properly formatted).

That being said, I understand the concern. What value would you go with for set_min/max_delay? Remember that clock skew is used in this calculation, which can be many ns, so what might seem like a loose constraint suddenly gets tighter. My feeling is if the set_max/min constraint is really loose, it probably doesn't hurt anything, i.e. if you do a min of -10 and max of 20, it's not going to have an effect on the design. I'm sure there are cases where I'm wrong, and I tend to assume there's not comb logic between unrelated domain transfers. If there is, the max may go higher.

I've seen users want to do something smaller on the max. The question I ask is "what does a failure look like?" For example, if you put in something small like 8ns for set_max_delay, can you show how a delay of 8.5ns causes a failure?