I replaced my battery after only 2 years as i dont use the car much and the original batterys are not much good!
nothing wrong with OEM batteries, they often last over 5 years - what does kill batteries is being in a low state of charge for long periods as the chemistry goes bad and they will neither accept a charge very well or release it readily.
Bosch isn't my favourite battery as I had one on my motorbike that gave up after a very short time, as did a Varta, I have had the Yuasa AGM (Absorbed Glass Matt - with no free electrolyte to spill if battery splits in an accident) on bike for nearly 3 years now and still going strong. I have a Yuasa 'silver' battery in the car, guaranteed 50,000 starts or 5 years.
Yuasa has more batteries in space than any other maker (satellites and space station) which is a tribute to their manufacturing standards.