I carry a 20 rounder in my pack, an 8 rounder on my hip and 9 in an elastic butt sleeve on the rifle stock.
Reason?
I packed into a new spot, only had google maps to work off, anyway there was a huge open area that must have been a land slip some time in the past, only small saplings and brush were growing on it.
When I arrived, it was much steeper than I thought, no where to put up a shelter or Bivvy, so I had to find somewhere overlooking that area and flatter to set up camp. I was also to collect water for later trips and store it on site. Collapsible water tanks are great!
As I left, I put up a dozen or more deer that I had not seen.
The place held huge numbers of deer due to it's remote location.
On a later trip, 4 of us went in, we shot 7 deer between us in 7 days. We could have taken double or more, but we had an incident where half of the ammo was lost in a river crossing. The rifle was recovered, the ammo or bag it was in was not.
This is why I carry all that ammo, if I had only the 9 rounder on the butt, we could have been up for some trouble.
10 shots of the same cal, 300WM, were used, our Sambar are tough and often require follow up shots as the terrain is harsh and tends to swallow deer for good if they run far.
It's only luck I didn't have my 338WM, cause there would be no ammo for the other guys rifles that could've ruined the hunt all together. The 338 was off having the scope base holes opened/threaded to 8-40.
I say you can never have too much ammo.........as long as you can carry it comfortably.
Cheers.