Sheila was only days away from her next injection so in effect what she had left would be of no use in containing/ controlling her illness as in fact because the dose had been lowered anyway the less it was the more dangerous in the sense that it was a large drop from what she had been originally signed up for.
Those who are given medication for heart problems who see a drop in their dosage more often than not suffer a heart attack, so why would anyone reduce the dosage of a vital medication ?
At death she was found to have in her system, an adequate and theraputic amount of Haloperidol, low to moderate doses of which have been found to be adequate for most severely psychotic patients, which would have been efficacious until her next dose, which I believe to have been due sometime the following week.
Regarding heart meds, my adored M. often had his changed according to what his doctors felt was necessary. The balance is all important. A theraputic dose, not more than, is all that's necessary.