I use the 75mcg patches and I am wondering how long that actually stays in my system. My doc has me putting on a new one every 3 days. Is that because it runs out that quickly?

I was on the patch and, yes, once the correct dosage was reached I replaced the patch every 3 days, presumably because that's when it stopped working. I'm sure your Physician isn't giving you too much and hopefully he isn't giving you too little.