I asked Haraki. I love his response...
First, some important elements that I think important for garments....
1) good pattern
2) good material
3) good sewing
Triple works means these 3 elements always make our garment right. I think it's important.
Also, like the Father, the Son and the Holy Spirit in Christianity, in the East, there is an idea of three element making this world - heaven, earth and man.
This idea is from ancient times. So I named triple works.