PbSO4 will harden with time, it does not really matter how the electrodes and separators are arranged it happens, it can to some extent be converted back by a long float charge and also is not as much of a problem where the amps drawn are low, it will result in the capacity of the battery being reduced, but we tend not to notice this with most applications. The golfer may notice he only gets 16 holes instead of 18 holes before the battery fails, and the mobility scooter may in the same way be reduced from 18 miles to 10 miles, but point is most people don't try to do 18 miles in a mobility scooter so until down to 2 miles unlikely to notice it has failed. In fact most applications are the same, stair lifts are rarely required to carry 18 people up the stairs in quick succession so unlikely to notice damage to battery until nearly on it's last legs.
With the caravan it is hard to work out what a battery has done, we tend not to count or time how long lights have been on, or how often the water pump is used, we may realise we can use the motor mover to get the caravan into it's parking space then it fails, but the time between getting into parking space often means doing and not doing the job also relates to last year and this year with 6 months unused and we simply put it down to old age rather than the sulphur getting hard on the plates due to poor maintenance of the battery.
Where hard PbSO4 is really noticed is the narrow boat, here we have a real problem, used every night and charged every day when engines are running first we would think no problem, however time is not on our side, it takes time to recharge batteries it does not matter how much power you have, so a 75% discharged battery will take something like 8 hours to recharge, a 50% discharged battery around 6 hours to recharge, and on average the boat engines are running more like 6 hours to 8 hours, so you need enough batteries so they are only discharged 50% and not 75% so they can recharge in time, and getting a shore power once a month to top the batteries up will really extend their life.
The other way is to push the energy into the battery quicker, stage chargers and pulse chargers can reduce the recharge time and reports from narrow boat users show these chargers can increase battery life from a year to 5 years or more as they ensure the battery has been fully recharged and not left in a part discharged states for in some cases months before they get shore power to fully recharge the battery. Today solar panels have really helped to stop batteries becoming flat due to self discharge, even a small panel in a caravan or boat window can stop the battery ending up as ballast by start of next season.
With open cells one can at least use a hydrometer to measure state of the battery, but with VRLA the volts can be miss leading, this is true of many batteries, with alkaline batteries often the output is measured using a small chip to be able to show state of charge, as the battery fails the charge indicator shows wrong info, ask mobile phone users, it is the same with simple suppressed zero voltmeter with lead acid, it gives an indication but will not show when capacity is reduced due to hard PbSO4 which will not convert back.
OK like not using a dimmer with quartz bulbs, we ignore the problems and put up with premature replacement, but to keep the battery good needs charging once a month.
