Same here, go 50/50 and add about a # smoked bacon per 10# sausage.

For pan breakfast sausage I use a 60/30/10 (60 deer or hog, 30 pork butt, 10 pork fat). IMO - pork butt just does not have quite enough fat.
Another tip is don't try to mix it by hand. Use a mixer. They are worth the investment.

We have always seasoned the cut meat prior to grinding. Comes out of the grinder as mixed as it can possibly be..

I quit mixing venison & pork a few years ago. I like using 100% pork now for my smoked & fresh sausages, just like the taste of the all pork a lot better. I use all feral pork and add 1# of bacon ends and pieces for every 4# of pork, turns out some very juicy/tasty sausages. The only sausages I make out of venison now are summer sausage and snack sticks. The rest of the ground venison is packaged as pure ground or 75/25 venison bacon burger.

I bought a mixer but seldom use it I like mixing by hand

Wild pig 60/40

Store bought 75/25

Venison/pork

Sure, I'll take some sausage. No! Not if you have to kill the piggy for it.

Man... if it was only that easy!

Definitely.
We throw all of the venison and pork chunks in a cooler, then sprinkle in the seasoning as someone hand mixes. Then drop it in the grinder hopper by alternating a piece of pork, then a piece of venison, etc. You can't mix it any better than that.