1) Check TDS in your area. If it's around 150, you don't necessarily need RO. UV+UF would work fine.
So in case you have an RO enabled Water Purifier & TDS upto 150, just keep pre filter clean and you should be sorted.
I live in Delhi and clean my Pre-filter every month. TDS here is around 150 so I don't change the filters. One (or more) year RO+UV+UF give same performance as getting new RO cartridges.
Also, a mechanic told me never to rub the sediment off the Pre-filter as rubbing damages the membrane. Rather wash it under high pressure and tap/pat it to get the sediment off.
2) I have noticed Local RO filters giving equally good performance as far as bringing down TDS is considered. I have a local brand installed in one of my rented out flat & it brings down TDS from 800 to 150. (This is in Noida)
3)Get UC Native RO. In long term, it gives better ROI than rest of the Water purifiers as the cartridge is self cleaning and it comes with 48months life (other brands have 12months)
Accept it as necessary expense, part of life.
Change your pre filter regularly, your ro life will increase. Pre filter are available at very cheap price. You can do this yourself.
Maintenance expenditure depends on input water quality. Try to install install a cheap optional pre-filter at water inlet to minimize damage to main water purifier.
Many times replacement alarms are triggered based on preset time durations rather than actual choking. Try to reset the alarm and resume functioning unless water flow stops. Maintenance personnel earn a lot of commission on replacing filters more frequently than required. Try to pre plan filter replacements based on ur actual water consumption and guaranteed capacity of filters