Yes, I have been taking warfarin since 2017. I still get iffy about it too. But, I have regular checks for my "INR" levels frequently. Mayo does use INR levels to check to see how fast/slow my blood is clotting. My INR level goal range is between 2 to 3. If anytime it's under 2, or above 3, they adjust my Warfarin Dosage to keep me in my goal range. Then, they recheck the level to make sure it is back in range.
This is NOT a blood draw each time. But, finger stick. So, don't be afraid of getting your blood work done.
Hope this helps! Pat