I think you will find, that your gear will expand to fill the shooting bag. So with a bag that size you will no doubt have enough tools, and gizmos to rebuild your truck along side of the road, with plenty of room left over for a good size lunch. Smaller is better, it helps you resist throwing stuff in the bag “just in case”. Believe me on a long woods walk, or on a trec , you will be done long before the end of the event. I have one about that size a good friend made for me. I noticed I shot much better on events I shot without my shooting bag on. Turns out it was just wearing me out. Besides a big bag is always in the way. A small bag worn up on your side above your waste is much better.
Hungry Horse