For me, shooting the bigger magnums, I wait about 1 minute between shots. And that's more for barrel life preservation than anything else. I am just an accuracy minded hunter, so squeezing the final .01% of accuracy out of my gun is something I don't worry about.
I have my Labradar setup so the screen goes blank 1 minute after the last shot. It then stays armed for another 30 seconds. It is during that 30 second time period that I take the next shot. During that 1 minute, I extract the spent case, check it for pressure signs, write down the velocity readout, and put the next cartridge on the follower. That makes it easy to maintain a slow and steady shot rate to minimize heating the barrel. Once I find a load, I will do a few quick 3-shot strings to gauge how the load will perform in the field. I know it is not perfect, but for me that seems to be the best balance of the various competing factors.