A good maintained bat , must come for 5 year , then it will last a year or more on continuous running , else a idle car will loose soon as after 5 year the cell life comes down.
One of my experience ,
1. One of my friend has a petrol uno , it has 37 amp bat as stock and accordingly it has a alternator. he change it to a 2nd hand indica bat (my indigo has 60 amp must be same for indica) , it lasted for 4 year to him. It was in indica for 4 years. So that amaron bat lasted for 8 year. On continuous running , it cranked the car well.
One of my query is ,doesn't that alternator ruin the battery as it has higher amp? It doesn't properly charge the bat.
2. In our omni it was for 4 years then we sold it . still its running in that bat
I guess it has to do with the fact that I stay very close to the Mumbai - Pune expressway ... the early days saw me set the alarm, get up at 0400 hrs, and drive past the Ghat Section and get back, just for the thrill of driving.
Then again the huge selection of hill roads and coastal stretches if you have a yen for the drive.
Would have done a lot more if not for my bike which gets its fair share of time, and an accident which saw me sidelined for 4 months or so.