I get 30 of the 10mg Percocets a month for chronic migraines and chronic tension headaches (headaches all day every day suck...).
They helped a ton until I got a medication overuse headache
(after ~3 or 4 months of daily use, in my case). Then I got into a horrible spiral of taking Percocet for a headache, which gave partial relief for 2-4 hours (usually), and was immediately followed by a worse headache. Lather, rinse, repeat.
So... moral is, more isn't always better, I guess. But yeah, 40 per half year is pathetically small if you get migraines or really bad tension headaches often and nothing else works. I didn't get addicted when I was taking 1-2 every weekday (and saving up on weekends to create a buffer). I got 20 or so sitting here, forlorn, while I try to get my MOH under control.
I trust you've tried all the tryptans, Migranal, muscle relaxants (if you get tension headaches), blood pressure medicine (beta blocker or calcium blocker (Verapamil is a favorite)), anti-convulsants (Topamax), SSRIs, TCAs, and whatever other crazy-ass guesses your neuro throws at you...