You don't just assume your car is going to run out of oil because you haven't checked the oil since the last time you started it -- you know that as long as you check it every 7,000 miles, or whatever the manual says, you do not have to worry about that. Why would a gun be different?
My van's transmission just died, the whole thing. It had barely 34,,000 miles on it. Just at the 30K mark, I had 30k service on it barely 6 months ago. Because the power train has 5 year/100k warranty, I was safe. They went in and discovered there was barely any transmission fluid left. I saw no leaks on the driveway either so I guess it somehow burned up. Every part except the housing had to be replace. Transmission fluid doesn't regularly do this and doesn't have be checked as much like oil.
Now, why would a gun be different?