Back in the day (about 15 years ago), it was quite common, and for sections of the borehole wall that couldn’t stand on their own, we relied almost exclusively on self-drilling.

However, in practice, when the borehole wall collapses, there are many areas where grouting is insufficient even with reinforcing bars in place, so this method has come to be used only for temporary structures.

Since double-pipe drilling is now the standard practice, the use of self-drilling has decreased.

The Ministry of Land, Infrastructure, Transport and Tourism has recently started using it again.

Although the reason is unclear,

I suppose it’s because it’s advantageous for drilling in places where machinery can’t reach.