What is the correct way to support an undermount sink?

I was looking at my present sink and it appears the lip of the sink rests between the countertop and a plywood backing which the entire countertop sits on. It is probably also glued on to the plywood as well. No other supports. Is this the standard installation method in Malaysia?

YouTube videos from the West show brackets screwed directly on to the countertop underside which support the sink. They don't seems to use any backing wood or boards.

Based on my survey for a new kitchen, most KC companies now seem to only provide chipboard as backing for the countertop and I am wondering how well this will hold up over time. If the cabinet is much wider than the sink, the chipboard may sag over time, and water from washing dishes may run on the sink lip and get in through any gaps between the countertop and chipboard.

This is leading me to consider top mount sink for my new kitchen.

Anyone else have such concern or know why this may not be an issue?

Anyone finding sinks which have sharp and more angular corners harder to clean and water drainage is poorer compared to the more rounded corner designs? See photos below.

Wow, sorry to hear that. I think rust is due to poor welding QC. i.e., metallurgical issues. The angular sinks are not pressed like the rounded ones, but welded along the edges.