Edit: Great Book! Wedges, Tapered Hinge, Dutchmans understanding and warnings; affordable too!
This is something you have to have some experience with, and then work out in the batter's box per situation.
The amount of wedging force needed; is partially going to depend on how thick the hinge is, also the hinge height (amount of leverage), or how far back hinge is will change things on same tree too. A farther back hinge will give backlean less leverage, but will also give wedge, less leverage. i think we have a strong consensus that the back cut should be perpendicular to the spar/ not slanted; especially in wedging. This gives strongest, most solid 'backstop' on the stump side of wedge to make sure the wedge force is unforgiving lift; and also more leverage too i think.
Most backleans i like a high line in for leveraged pull forwards, wedge is help and more or less a safety / chock against sit back; but line does a lot of the work. Full side face with no dutchmans for ease of hinge movemeant. Wide across hinge for less resistance against folding forward. Tapered hinge for sideleans; so that hinge steers and all / as much as possible the exerted force of wedge and line serve forward into face squarely and quickly; not wasting a drop of that force for steering. If wood / hinge can't be trusted / completely; then help steer with wedge / line some.
The the part of force exerted with wedge / line that goes straight into face strengthens hinge giving another multiplier of your efforts; that pulling direction to steer against sidelean doesn't give. Tapered hinge uses the increase in forward force even better to steer, by placing tension fiber farther from compressed pivot of hinge (distance leverage wise increase), and more inline with spar (anglewise leverage increase); so leverages your forward force better multiplied 2 ways.
Those are just a few of the considerations that need to be maid on the spot; not necessarily a novice sport!