Just wash weekly and wax quarterly. It is sufficient. Cost wise RM600-800 per year

PPF and Coating will not save the paint from stone chips or scratches.
Cost wise RM3k per coating that lasts for 3 years, but requires maintenance.

With RM3-4k, you could probably get a new fresh paint after 5 years.
And in the event of minor crashes, the coat and PPF will be gone.

Yup. The coating is more like signing a deal or membership at that specific detailer. You're under contract if you need to maintain the coat.

For wash and wax, some shops do have memberships but the cost breakeven point is usually not much different than walk in. It's worth it if you plan to send the car wax monthly. For polish, do it once every 2 years based on the paint condition. Only when there's too much swirl and micro scratches can see by naked eye. If you do polish every 3 months, your paint will get thinner and thinner and you'll see the base metal soon. A colleague of mine did that to her City. In 3 years, the A pillars paint are gone and faded off.

Polish = Sanding. If you sand a block of wood daily, eventually the wood will turn to dust