@catapillar
By minimum correction dose, I meant taking less than 'x' units, has no detectable effect. I know this sounds strange, but if I take less than 3u, it does nothing for me. So I'm wondering if there is some level of loss/unusable insulin, either physically or biochemically, which is more pronounced when injecting only very small volumes.
My basal is pretty close to correct. Occasionally I will drift down by up to 1mmol/L overnight, maybe once or twice a week.
As for the range thing, I guess that's focused at people who can't perfectly estimate what carbs they get in a meal, like me. (Eg: estimating rice served at different levels of density). Unless I made it myself or it's from a place that has standardised meals, I can't yet estimate with the necessary accuracy. (IE: within 1 unit according to my ratio).
So in that case, someone would either need to overestimate insulin and take on extra carbs as necessary, or underestimate insulin and correct later.
I'm wondering which is more common/preferred. Or maybe most people just don't think about it and wait to find out afterwards if they guessed high or low.