https://www.youtube.com/watch?v=FwGWN0AyoFgGreat video from the University of Guelph on how to do splits with confidence! You have choices that don't involve a walk away split.
At the 15 minute mark, of the video, looks like me trying to pry apart heavy stuck brood boxes!
The demonstration is during a honey flow with supers on. I am not sure that is when I would do splits as one strong colony will collect more honey than two weaker colonies.