Authors of human behaviours try to stereotype the behaviours of the whole society so that it can fit into their theory. You can do that with a very consistent society. But Singapore, like most other societies, have evolved.
You may not find this in the textbooks but if you are a local, you will notice this trait..... there are 3 groups of people. The old guards, the baby boomers (born 1950s to 1960s) and the new generation, all having different behaviours. When living in the same household, the theory becomes very complicated.
Back to your question, you qualify it by concerning Banking relationships. Then I would say that for most Singaporeans, when it comes to money, it is very individualistic. Some may have a big heart in donation or sharing, but when it comes to managing their funds, they don't want others to be involved