Now I have purchased several boxes. Not sure why, except that I felt I wanted to stock up on them. I have several boxes for each of my main hunting rifles (.243, .270, and 30-06). However, they are still collecting dust.
I bought my first box for my .243 when I bought her three years ago to replace my 30-06 for the smaller deer here in Oregon. Even with sighting her in the initial year and once last year, I still have rounds remaining and I have taken my deer every year.
All I can boast is one round/deer per year. At this rate, I have enough to hold me out until the Good Lord comes or I die. I have even resorted to shooting the odd coyote and bear to use up some of the 30-06 shells that remain from a box purchased before they started putting internet addresses on the boxes.
So from my point of view (my .243 only holds four, if you have one in the chamber), six rounds is more than enough for a hunt. If you haven't made the kill in six shots, you may want to go back to the firing range for some more practice.