For absolute safety you are correct-

With factory bolt rifles I have only ended up 2-3 grains over max without other signs of excessive pressure with sticky bolts, primers problems, or brass expansion.Hunting for max accuracy with backing the bullet off the lands and dropping the charge usually finds that powder charge down signifigantly.If the measured velocity is TOO HIGH for the reload you will have too much pressure no matter what you notice with the brass!! I have an accurate 270 with a longer throat that likes a hot load and tolerates it well reaching slightly below standard 270 max velocities.

I will say that if the bolt rifle has a tight or MATCH chamber, everything goes out the window and usually you never see the max charge allowed. I have a match 308 bolt gun that taught me that lesson. If factory ammo is tight going thru the gun--BEWARE!! Starting 15% down and working up is good advise on those guns.

For Big Doubles I will assume the powder charge should be 10% down from max and you work your way up to the recommended max accuracy/regulation or until pressure signs stop you. I bet there isn't a Buff alive that would notice the difference in backing off 50-100fps if your load is accurate and you put the bullet in the right place.