A fully charged and cool temperature battery is a happy battery.
Without knowing how well any vehicles charging system is charging the battery, reports of longevity are unfounded.
Want to know how well your charging system is charging a flooded battery with removable caps, get a quality Hydrometer like the OTC4619.
Another method for determining full charge is how many amps a battery accepts when brought to 14.5ish volts. A fully charged battery will not requiremany amps to get to 14.5v and those amps shoud taper to low levels.
If the battery takes a long time for amps to taper to less than 0.5% of the battery's 20 hour rated capcity, it is not fully charged. The more amperage it accepts the less charged it is.
And a happy battery is a fully charged battery, and a happy battery lasts a long time.
Reports of poor batery longevity in mild climates are from a vehicles voltage regulator not getting the battery tom and hoildig a voltage in teh 14's for long enough to return the battery to 100% charged.
Honestly a depleted battery is unlikely to ever get fully charged to 100% by a vehicles voltage regulator, which controls the alternator. About 3x as many amps will flow into a depleted battery than will flow at 13.6v.
Those wanting excellent battery longevity are wise to put it on a good charger every so often to insure they are fully charged, as the vehicles voltage regulator is primarily concerned with not overcharging a battery, rather than fully charging it as quickly as possible, or keeping it fully charged.
many chagrers will also throw in the towel prematurely and flash the soothing green light. A hydrometer will prove that many automatic chargers are not completing the task. however if left at the lesser float voltages for a longer period then they can eventually get the job done, on a still healthy battery.
It is highly unlikely that low charging voltages sub 13.8v will ever max out the specific gravity on an abused ( chronically undercharged) battery. Voltages in the high 14's might not be able to do this on an abused battery. Any attempts to fully charge the battery will yield a longer lofe than simply believing the vehicles voltage regulator/charging system are all powerful instant battery chargers that can keep a battery as healthy as possible for the longest period of time.
It is also unlikely a 'trickle' charger will ever get an aged battery to the voltages it requires to max out Specific gravity.
Get the OTC4619, it will prove that the most charging systems are not getting a battery to full, and getting to 98% chagred is good, but only half as good as getting to a true 100% state of charge.
I've got ~600 Deep cycles several hundred shallow cycles, and many thousand engine starts on a Northstar AGM, which will turn 4 years old in November. It is a high quality battery but it would never have lasted this long/ this many deep cycles, if I could not recharge it fully, promptly, often.
Lead acid Batteries are basically murdered by chronic undercharging, and Excessive heat. Keep em full and fully charged andf they will last a surprising amount of time. Let the vehicle take care of them and 3 or 4 years is all one can really expect.
Those reporting higher lifespans have vehicles that likely hold the battery at higher voltages for longer before reverting to float voltages, and have lesser parasitic draws, and owners who use less battery power with the engine off, and also do not let the vehicle sit unused for long periods of time so the parasitic draws are basically deep cycling the battery.
Gettng a 50% charged battery to 80% charged can be done in under an hour at higher charge voltages, but 80% to 100% takes about 3.5 hours more, and that is when brough to and held at 14.5ish volts for those 3.5 hours.
It is highly unlikely any vehicle will hold a battery at 14.5v for this long. And indeed 14.5v held after the battery is fully charged will have it using a LOT more water, and causing positive plate degradation, which on starting batteries are already pretty thin porous and fragile. Exposed plates from water loss is pretty much irreversable capacity loss.
Charge your batteries to a true full regularly. Do not expect the vehicle's charging system will do so, even on a longer drive, as full charging takes a lot of time, at higher voltages, and an extremely long time at lesser charge voltages. It does not matter of one has a huge alternator. The alternator is controlled by a voltage regulator, and the battery dictates how much amperage it requires to be held at any specific voltage. and the vehicles voltage regulator does not care about fully charging a battery, it cares about not overcharging a battery, and thus is timid, as timid is safer.