Depends on how I and the gun are shooting. If I place two shots on top of each other (with a minute to cool between each shot), I will adjust my scope as needed. If my two shots are not consistant, I will get a third or 4th shot in to get an average.

It is not uncommon for a standard hunting rifle with magnum loads to start losing accuracy after 3 quick shots. I would definitly let the gun cool down for several minutes (maybe 10) after a 3-shot group. If you are going for consistancy, you do not want to get in a hurry at the range! Take your time!