I realize your knickers are all knotted up Jem, but I really can't take credit for the invention of the "making the back-cut first" method when using tree-jacks, or pounding over a hard learner. I myself was taught this technique when I was 16-17 yrs old, and folks had been doing it for a very very long time before that.
A video of Bucking Billy (love this dude) starting with a back-cut on a hard leaner. Again just as important as the method is the execution of said method. You can clearly hear and see when his wedges are maxed out, and no longer moving the tree. He adds another wedge and gets a little more movement. He then he adds his undercut which gives the movement that he has already created a place go. Back to the wedges, and through thoughtful hard work he slowly continues banging over this tree and letting his wedges tell him when they are maxed out, and when he can begin double stacking. I got tired just watching this, but Billy persevered and got it done! I think I am gonna buy that fella a Salt Creek Hi-Jacker for christmas!!!
This is why always trying to use at least 2 wedges is so important. It is exponentially more effective, and if you spit a wedge your tree will not sit back on you, and possibly go backwards on you.