I keep a stock of maybe a couple of hundred quills at any one time, and harvest more whenever I get the chance (usually when friends are culling geese, or just off roadkill). Rather than drying, I harden mine in hot sand. I tend to cut a new quill for every job, and almost never trim or re-cut quills, which may just be a facet of my rich supply.

I do cut the tip of my quills the opposite way to that recommended by Johnston. (Just grabbed my copy and checked; Hadn't looked at it for a decade or so.)

At the moment, I'm suffering from bad inks. My best writing ink (1880's era Stephens blue-black) is losing its lightfastness with age, but all the modern inks I have tend to gum up my quills with gunge. Experimenting with chinese ink sticks.