I have a confession to make: I kept the Navigator sensor in for two extra days — for a total of seven days instead of five.
The sensor adhesive was sticking so well, I was pretty sure I could get away with it. And I didn't have any problems with the accuracy, either. In fact, I'm not really sure why they want you to only use the sensor for five days.
To get the extra couple of days, I stuck my thumbnail into the back of the sensor and popped the catch that keeps the transmitter locked onto it. You have to be very careful when you do this, so that you don't wreck the adhesive or pull the sensor out of your skin. You might want to look at how the sensor and transmitter fit together sometime when you removed a used sensor, so you know what I am talking about.
Anyway, when you do this you really only get an extra day and a half, because you have to go through the 10-hour initializing period again. But in my case, I wasn't as concerned about my daytime sugars — I wanted to fine-tune my Lantus dose by looking at my nighttime sugars — so I just restarted the sensor shortly after I woke up on Monday.
I ended up being glad I did it. I was able to tell quite a bit by looking at my sugars Monday and Tuesday nights, and I think I've hit on the correct Lantus dose. It was going so well, in fact, that I was really tempted to leave the sensor in for longer — but not knowing what would happen, I reluctantly removed it this afternoon.