they come to find out your INR is 1 or when you bleed out and come to find out your INR was 5.
I'm no internal medicine doc, but even though some studies show a 12-week interval to check INR was non-inferior to a 4-week interval, the official guidelines for the drug suggest the INR be checked every 4 weeks.
Warfarin is a crappy drug in a lot of ways.