Lovely patterns, but I don't want to make an entire hat just to frog it because it won't fit. Gauge is essential, or at the very least the hat's dimensions, to ensure that my hat fits the correct size. Just because the author can use an H hook and get a hat to fit a 0-3 months doesn't mean I can. It would be a waste of my time to make a preemie size hat with the same hook if I was intending it for a 2 month old. Or what if the 0-3 month dimensions are to small for the particular 2 month old I'm making this for and I should have made the 3-6 month old hat?
It would ne nice if different sizes were given for each hat. I am experienced enough to do this for myself, but a novice wouldn't. Simply using a bigger hook to get a bigger hat doesn't always work.