Compared to countries like Australia which uses a point-based system to calculate your PR application, in Singapore, your PR approval is at the sole discretion of the Immigration and Checkpoints Authority (ICA).
To make matters worse, the ICA doesn’t justify their reasons for rejection which may leave applicants feeling frustrated despite following their guidelines.
However, Singapore is still open to bringing in new PRs and citizens because of an ageing population. The ICA approval may be stringent but new applicants can take the necessary measures to improve their profile and approval chances.