Honored Contributor
Honored Contributor(Expanding on the slippery slope comment...)
I've seen customers do this in the past and say they had to for another companies devices(many years ago, so take with a grain of salt, and I really don't know if the customer was right or not). But I have seen people pad numbers like this at big companies. Designs get passed around and another group suddenly gets asked if they pad their numbers of not. Or a design has trouble meeting the padded requirement, and they spend all this extra time trying to close timing, and questioning why it's there in the first place, which nobody really knows. (One other thing I've seen for X designs is whereby they say the fitter will do better if you over-constrain your critical paths, and I've seen people try that with Altera devices. In general you shouldn't have to do that, as the fitter already knows what is critical, but the worst case is you know have an area where the design could fail the over-constraints but pass the timing you want, which causes a headache for analysis...) Just some thoughts...
