Intent is a very important thing. Unfortunately, people can have very good intentions and their actions have poor results. It is shockingly common to hear "I didn't intend for that to happen" in daily conversations. Failing to align your actions and intentions makes it very difficult to successfully perform magic. Brutal self examination and honesty is required of us when ever we sit down to do a spell or any other form of magic.
I say it is brutal because we must not give quarter to self deception. If we can not say with full certainty that we intend for XYZ to be on our karmic debts, then we shouldn't engage in it. This is not only how one take the measure of a honest person but how we should weed out that which we should not engage in. All of us have different tolerances for unpleasantness. We all have different tolerances for hardship.
We must keep these things in mind when we consider the possible outcomes of our magical actions. Acting with intent and self-understanding allows us to be successful. It keeps us from hamstringing ourselves subconsciously due to a misalignment between intention and act. It keeps us from taking on karmic burdens that we simply can not handle. And, most of all, it keeps us honorable.
That, however, is all my opinion on this. It is the fruit of my own learning experiences. It may be that somewhere down the road, my position changes because I have learned something new.