I've been baking and decorating cake for some time now, and I guess never thought to ask how other people do it. We you have a large pan that is going to require multiple cake mixes, Do you mix all together or do you mix 1 cake mix, pour into pan, mix another cake mix, pour into pan, and so on?
You could do it either way it would depend on how big of a kitchen aid you have. If you put it all in one big bowl and use a hand mixer that would work as well.
When I make multiple mixes I make them two at a time in my KA. Turns out perfectly