Good question. The short answer for me is only as much as I will shoot up within a year or so.
Here is my completely unscientific reasoning. Several years ago I commented to a guide who does a lot of competition shooting that when I was preparing for our hunt I shot a few rounds to check my zero and was disappointed in the accuracy. Thinking there was something wrong with my rifle or optic I checked all of the usual things like action screws and cleaned the barrel then switched scopes none of which solved the problem. At this point I needed to load some more ammo and voila, accuracy restored.
My friend said he had seen the same thing with his competition rifles and theorized that the culprit was possibly bullets welding in the case neck and messing up the neck tension. I have never tried to prove that but now only load up smaller quantities.
Be interested if anyone has experienced similar or has proved/disproved this.
