My Tracer is only 2 and a half years old and still has the original battery, but my FZ6 Fazer which I bought new in 2004 only had the original battery replaced after 11 years, including over a year where it wasn't started once.
I have an Optimate 3+ that the Fazer is permanently connected to when not being ridden, which is most of the time. It only has 57,000 km on the clock after almost 16 years so it hasn't worked hard.