I saw a video lately on this type of split: a guy has a 2-deep hive, with each deep's frames well-worked (brood, honey, etc). He just took off one deep, added a medium to it and covered it, and added a medium to the other deep, then covered it. That was it?! Is it really that simple? Maybe -- in my mind -- I've been trying to make it a lot more complex and voodoo-like, mixing/matching frames, etc.
Yes it's that easy, well kind of, if all goes well.
The med is not a necessary part of the split. It was added to give each hive more room, which may or may not be necessary.
A walk away split; usually a 50/50 where you can separate the boxes of the hive (providing each box has equal parts of brood, honey pollen) and divide and make two hives or separate by frames into two boxes (have more control to balance each). The box with out a queen will make one. The box that has the queen will continue to grow. You do need to check both hives in 30 days to verify they made a queen. Screen shim combine them back if one does not have a queen. If you move each hive to the right and left of the original you will reduce the chance that most bees will return to the old location. Your honey production will be reduced but the goal here is to make hives not honey. I've also done 33/33/33 walk away splits when the hive is really robust.
I do walk away splits if I can't find the queen when there are swarm cells. One of the splits will still swarm but it may be less bees they take.