Asking for perfect outcomes in witchcraft
Bit of theory; take it or leave it, etc.
One fun thing about witchcraft is that spells often manifest literally. When your objective does not match your programmed intent, spells tend to follow intent.
I tend to view intent as being like an ethereal wireframe that power fills in to make it solid and real.
Whatever the shape of your intent is, that defines the limits of the spell.
However much power you can conjure determines how solidly the intent can manifest.
That means if you ask for limited, restrained outcomes, that will tend to be the kinds of outcomes you will get, no matter how powerfully you work the spell.
Casting a spell with an intentional ceiling built-in that limits its effects will actually limit its effects. There is no reason to assume that if you cast a spell extra strongly or extra well, that your intent will be unwound and replaced by a different intent you never specified.
Not to psychoanalyze a hypothetical audience, but I suspect that some witches choose limited intents because they think it's all they can accomplish, thereby creating a self-fulfilling prophecy.
I do think a lot of witches who are down about their own abilities are truly working with power, supercharging their own spells - but those spells have intents like "get him to bother me less," instead of "sever his attention from me now, from before the beginning of time to beyond the end of time, in every time that existed, in this dimension and in every dimension, and cauterize his severed attention so it may never regrow, that in this life or any life until the end of time, neither he nor any version of him may observe me, think about me, or interact with me or any version of me that has, does, will, or could exist."
I get on these kicks, and my current one is, if it's a milquetoast intent ("get him to bother me less") you may as well be putting like 20% or 30% effort into it and not exhausting yourself at all. Honest question for witches who are constantly exhausted from doing magic: have you tried putting in way less effort? You may be surprised at what little power it takes to accomplish simple things.
But if you're set on going all-out, giving 110% every time, and being almost nonfunctional for a week after every spell you cast, you might as well go for grand cosmic intents that seek to rend the fates beyond the gods themselves. How do you know you can't, if you've never tried?