My old elk camp it was split evenly. Everyone kind of did their part. Some owned the cabin and paid the taxes, others of us packed more than our fair share and shot more of the animals. At the end of the day, everyone shared the butchering costs and everyone got a fair share of the meat, that way most people had some elk in their freezer every year. Hard to eat a whole elk anyway.
This was a pre-arranged deal, so everyone knew what they were getting themselves into when they came to camp. One guy got one who didn't want to share after he got it... He was never invited back.
In other scenarios or camps things are different, but I have found myself wondering what I would do without people sometimes. If you shoot one and think, "That was pretty easy and I could've done it myself with out much issue" give them a little for their help and thank them and pass on the favor. If you find yourself thinking "my GOD I have no idea how I would've done that without you", you'd better pass them a little bit more.
I tend to prefer the share evenly and share butchering costs one, but you have to get buy-in from everyone before hand. Its an nice fun easy way to do it though.