My downstairs co2 detector is on continuous power since I piped gas into the house last year when switching some appliances to propane my better half insisted we get one. It has never gone off.

I have a smoke detector in my downstairs hallway that drives me nuts. The hood over my stove takes all air directly outside when on but it has a huge design flaw. It doesn't stick out far enough over the stove so the two front burners aren't really ventilated very well. I usually cook on the front burners so that's a problem. The biggest issue is when I open my oven. It almost always sets the smoke alarm off. No visible smoke. Must be very sensitive to both temperature and smoke.

I try to fan it with a large magazine or similar and that often clears it up. Run the hallway bath fan which helps to vent it out. Just very annoying.

The ones in my basement and the combo smoke/co2 upstairs are the worst for the little "chirp" on low battery. And yep. It's usually in the late evening.

Can't hurt to periodically replace them. Whether it's really a necessity or not I can't say. I've never had one continue to chirp with a fresh battery. 

My hunch would be that the detectors will continue to work longer than any time duration mentioned by the manufacturer, but aside from batteries the liability to the maker is no longer in effect if  there should be an issue. TBH I never looked to see what the guarantee for those is. JMOP YMMV.

Be safe!

I had to look up Ichiban lol. There's a place around here called Hibatchi that's the same kind of thing. Good food, but yeah, it's kinda close to the hot stuff.