If the pond has 50 sunfish that average about 6 inches a piece and about 5 bass that are from 12-15 pounds, I would probably get by on most days with my cane pole and 2lb test.
But every day that I fished there, I have a chance to hook the 15lb bass, even though I will be hooking mostly sunnies.
If I hook the 15 pound bass on the cane pole, I'm SOL. If I hook the sunny on the baitcaster with 15lb test, I can still put him on the dock.
The 30-06 is fine for the 120lb doe who is broadside at 50 yards. The 223 is not fine for the 300lb buck who presents a quartering-to shot.
And no, the buck of a lifetime is not going to give you an hour and every possible shot opportunity. Maybe the doe in the food plot or at the feeder will. But the buck that will be your crown achievement will only give you a fleeting glimpse and you better be ready and prepared.