Unless you have something like a transformer plug, I'm not sure why you would buy adapters rather than change a plug.

There was some stuff on here about how legally you need an electrician to change a plug. If the house burns down and I've changed them myself I might not be covered. The adaptors cost about $2 each in Singapore - probably cheaper than a new plug. Certainly cheaper than a new house.

Legally in Qld at least you have to get an electrician to change a plug or it may invalidate insurance in the event of a fire.
Its one of those topics that comes up regularly, and the links to the legislation are here somewhere - try searching posts by Cresta57 on the subject

I would also be concerned about the validity of using overseas power extension leads in the event of a fire caused by an electrical fault. Nobody is likely to question whether you changed your own plugs but if there is evidence in a fire of non compliant equipment then personally I am not sure you would have a leg to stand on.

And just from the safety point of view, adapters are not a good idea for full-time use. They are prone to overheating if something goes wrong and that can start a fire. It's never a good idea to install an adapter somewhere inaccessible, especially if you leave it turned on the whole time.

And adapters are not usually suitable for earthed appliances. Particularly the small ones that effectively swap live (active) and neutral around.

That's a good point. I had a standard double adapter overheat a week or two ago. Fortunately it was in a very visible place and I actually heard it crackling but not befoe it had melted around one of the pins.