Absolutely positive, I started at a standard weekly dosage and got E readings of 700 pg/ml, and blood work showed my albumin levels too high. We cut it in half, exactly halving the mid-week measure to 350 and then in half again to get down to the low 200s which is a number both I and my endocrinologist like ok.
For accuracy, ISO 7886-1:1993 dictates that accuracy should be +/-5% for volumes greater than half the syringe capacity, however as a 3 ml is probably being used to deliver 1/2 - 1cc for most im injections, the accuracy is probably less.
Again, it really doesn't matter, 10% accuracy is more than good enough for estradiol. And I agree one can do better than "standard" but then I'm a scientist/engineer and prefer to state accuracy conservatively.