In my experience, it varies so much from chamber to chamber and brass composition between brands. To me Norma brass has been forgiving where I don't see much change, and older Lapua brass used to seem the same. Using newer Lapua brass today I seem to get a 10-15fps increase, same load, on once fired brass, but it could be chamber size also. Other than my 7 saum, which I shoot Rem brand brass, Lapua is all I am firing at the moment.
On a 3000 fps rd, 30 feet more per second is a 1% increase, not much in the grand scheme.
I should add, i am always prepared to pull .1-.2gr of powder on fired brass.