It's hard to imagine needing more than three rounds of 300 WSM.
Then there's pig hunting... But to be honest I would not rapid-fire a magnum rifle that I liked. It wouldn't take much of that at all to crystallize the throat area and ruin the gun's accuracy.
For pig hunting situations involving long strings of rapid fire, I'd feel better off with a .308 Winchester.
With the 300 WSM, another tack would be to use starting loads instead of max loads. That should give you the equivalent of max 30-06 velocity, and it won't be so hard on the barrel.
Some Savage shooters note that barrel swaps are easy and inexpensive with the Savage, and don't worry about this issue. - They've got a good point, there.