Dust collects deep in the chamber of detectors, and can be difficult to clean. Best to replace all of them, they are not too expensive.

At least if you know which one starts, it may be in a dusty area and get dirtier than the others.

They are probably all interconnected, so one goes off they all do.

An area that has a lot of moisture , like a basement, may aslo cause nusinance alarms.