I have only made a couple of flat hats, but lots of hats overall. I looked at the pattern and I take it that it is starting at the top and working to the head band.
- If you want a tighter or looser fit, bind off a little before or after Row 72. If you want to take it off the needles to try it for size, be sure to put in a lifeline on live stitches using a thick yarn."
I'm not exactly sure what that means. I don't think just making the band longer would make the size much different.
But consider this:
Keep increasing to Row 50. Medallion’s width should be at least 11 inches. If it's 12 or 13 inches, that's even better. If it's smaller than 11", keep increasing the medallion.
So it sounds like after you have done the medallion part if the size is not as large as you'd like that you can keep increasing it the same way you did before until it is as large as you'd like. Thats for the flat part of the top.
I would think that, likewise, as you approach the head band that if it is small enough just don't do all the decreases that it says. I didn't look closely enough to see how many stitches you lose with each decrease row, but you could stop after a given row, or if you need something between what two rows of decreases would give, perhaps the last decrease row you could only decrease at every other spot or something like to arrive at a size between what regular decrease rows would give. When the size you'd like is reached, just switch to garter stitch and make the band the length you'd like.