I hadn't explicitly considered the interaction between location of correction in the stroke vs location in the boat relative to pivot point before this discussion - very interesting.
Think of the examples of a stern paddler, a bow paddler, and a centralized solo paddler sitting at the pivot point.
The stern paddler is behind the canoe's pivot point, so he can correct the canoe toward his on-side even if he does a pry/pushaway in front of his body instead of a J pushaway behind his body. Any pry he does from his position will cause the canoe to yaw toward his paddle side (= correction).
If the centralized solo paddler does a pushaway in front of her body and pivot point, the canoe will yaw even further to her off-side (= anti-correction). If she does a pushaway behind her body and pivot point, the canoe will yaw and correct back to the paddle side. If she does a pushaway exactly aside the pivot point, she will effect a perfect prying sideslip to her off-side with no yaw either left or right.
A bow paddler significantly ahead of the pivot point can't correct an off-side yaw no matter whether he places a pry/pushaway stroke ahead, aside or behind his body. All pushaways will yaw the canoe even more to the off-side (= anti-correction). He can correct with a pulling stroke (draw) placed ahead, aside or behind his body. Ahead of his body will be the most effective, for the same reason @lowangle al says this:
The further back in the canoe the correction is done, the less correction (and the less energy) is needed.
Wherever the pivot point (= fulcrum) is in the canoe when you are paddling from the stern, you will have a longer lever arm the further back you put the paddle blade.
By leaning and carving towards your paddle side you can sometimes eliminate the need to do any correction. The other day I was out in my 20' White and was carving towards my paddle side so hard that I found I was doing a sweep to keep going straight and had to dial back on my lean and carve.
Yes, we've discussed this in other threads. With a heel (lean), some hulls will carve more strongly toward the paddle side with a paddle-side heel while other hulls will carve more strongly toward the paddle side with an off-side heel. When you get a paddle-side carve started, you can paddle forward without any correction if you learn how to balance the force of the carve with right amount of uncorrected forward stroke force.
This is sometimes called the "inside circle forward stroke" (by Tom Foster and Charlie Wilson, for example) because you are actually not paddling straight forward, but almost imperceptively around the circumference of a huge circle. I sometimes call this the "carve balancing forward stroke."