The reason I didn't get tested was purely financial -- no doctor, not enough to pay for labs, etc.
I've probably been pretty lucky -- now I have two meters, but need cuvettes and tenderlett to do the testing.
I was stable with 7.5 a day, every day, for many years. For most of the time, I'm still doing 7.5.
I will be changing my water intake soon (moving over to alkalinized water, once I can afford the machine) and my INR may change, so I'll be testing weekly until stable.
(BTW: I'm still trying to put together a non-profit for people like me who couldn't/can't afford testing, and that charges a few bucks for people who CAN, but don't have a meter. I'm still working with some of the manufacturers and others to try and make this happen)
BTW - someone sent me a private message but it didn't open - please re-send.
Thanks