an art that takes more than one week to master
Imagine a training centre in the source country where fifty to one hundred young women are "trained" to cook for their future employers in Singapore. Some will stay for one week and some for up to one month. The instructor could be a former domestic worker who learnt how to cook for her former employer in Singapore. But given the time and budget constraint, the training may not be of an acceptable standard. Actually, the "training" sessions are more like demonstrations. It is like learning to cook by watching a TV program, only less effective.
The employer of a first-time employer would probably have to teach the newcomer the basics of cooking. Or get someone else to do it for her.
But an hour or two a day over a period of two weeks or so is really not quite sufficient for an inexperienced young woman from another country speaking little or no English to learn how to cook. Imagine a young Singaporean learning French cuisine from an instructor who speaks no Chinese, Malay or English
Experienced FDWs who have worked in Singapore before, usually know how to cook Chinese or even western food with varying degree of proficiency. If they have a liking for cooking and have used a recipe book as an aid to learning, perhaps all she needs is an opportunity to experiment with different dishes and styles of cooking.
At the end of the day, even if the new employee is experienced and highly commended by her previous employer, what she prepares may still not be to the new family's taste and the latter should be more patient and provide useful comments so that the new "cook" can adjust her cooking to suit the new family.