Anecdata, I recently had to replace batteries in several smoke alarms. 3 were Duracells and 2 were Rayovacs. All Duracells were from 2016/2017, i.e. assuming they were installed right away they lasted around 5 years. Rayovacs were from 2010 and 2011, despite both brands being rated for 5 years. It is possible that old Rayovacs were installed around same time as new Duracells and both lasted around same time, still makes for an interesting datapoint.
Just as a bit of feedback, for safety equipment like smoke and CO detectors, standard guidance is to replace the battery at least once a year. (Unless you have an integrated 10 year battery that will last the life of the detector)
If you live in an area that follows Daylight Savings time, doing it then is best so that you remember. Otherwise doing it during the Operation Edith drill for Fire Prevention Week is the next best.
Rayovac was bought out by Energizer not too long ago. They used to have a 10 year no leak guarantee, now they leak in a few months as I've learned the hard way.
