In addition to the age of a battery, one of the most common causes of battery terminal and cable corrosion is the slight draw of the electronics in a vehicle. Older vehicles equipped with the old-school radios which had an on/off switch were absolutely off, while pretty much everything today is built with what is commonly referred to as "soft touch" on/off as well as a separate circuit for radio memory.
The more little circuits that require low amperage draw for maintaining memory, gps location, soft touch, etc., the timing for maintenance will increase accordingly. Most modern heavy equipment will have four large 850CCA batteries and require servicing every six months or less - and this is because they have and Engine ECM, Turbocharger Controller, DPF, ABS, Dash Controller, Cab and HVAC Controller, GPS and Data Logger (with some also equipped with interface so the Home Office/Shop is able to perform diagnostics while the unit is on the road)..... and Agricultural has even more riff-raff.
As well, modern wiring and cables are manufactured with severely lowered standards. Not only is the quality of the copper strand marginally passable, the coating is porous and permits ingress of moisture along the entire length of the wire or cable.
If you want a quality wire, you now have to request for what is called "Low Oxygen Copper Wire." This is a term not heard of until twenty years ago - and even now, most parts people give you the deer in the headlights look when asked, then when or if they locate such, they are terrified to inform you of the price (about three to five times the "normal" stuff.)
Case in point: how much corrosion of the electrical did you see on vehicles up to the 1980s? Quality in manufacturing is a term with absolutely no meaning these days.