you have to count them by the leaf. i personally would throw out any plant that has more than 5 easily visible mites per leaf. there's many more eggs and babies that you can't see with your eyes though. once there gets to over 40 mites per leaf they start to go to other leaves and plants. it's not uncommon for a mite to spend it's ENTIRE life on one leaf. so personally, when I know they are traveling to more leaves, if you don't do something QUICK you will lose the battle.
I don't know what your life style is TTS, or what your goal is, but I want only the best. If that means I have to throw 3 months of growing away to start over, I would. It's my own personal hygiene I care about, I don't want to fucking smoke dead bugs. If you're selling the weed, that's another story. Get it?
To me it sounds like you lost the battle a long time ago personally.
Even though you can't see it, the inside of your buds look like this...
